Question 69·Hard·Boundaries
Leafcutter ants cultivate fungus gardens inside their nests; the ants provide leaves to feed the fungus, and in turn, the fungus nourishes the colony. Researchers studying this symbiosis have observed that the metabolic waste produced by the fungus—especially ammonia—is toxic to the _____ they remove it through a specialized ventilation system built into the nest architecture.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation and sentence-boundary questions, first test whether the words before and after the blank are each complete sentences (independent clauses). If they are, eliminate options that use only a comma (comma splice) unless there is also a coordinating conjunction (for, and, nor, but, or, yet, so). Then, recognize conjunctive adverbs like "however," "therefore," and "consequently": when they connect two independent clauses, you generally want a semicolon (or period) before and a comma after the adverb. Use this pattern to quickly narrow down choices and select the one that follows both the grammar rule and the intended meaning.
Hints
Check if both sides of the blank are complete sentences
Cover up the blank and read up to it, then start again right after it. Do both parts have a subject and a verb and express a complete thought?
Think about the meaning between the two parts
The first part says the waste is toxic; the second part says the ants remove it. What kind of relationship is that—contrast, addition, or cause-and-effect?
Recall how to punctuate with words like "however" or "consequently"
When a word like "however" or "consequently" connects two complete sentences, you usually need a strong mark (semicolon or period) before it and a comma after it. Which choice fits that pattern?
Step-by-step Explanation
Check the clauses on each side of the blank
Read the part before the blank: "Researchers studying this symbiosis have observed that the metabolic waste produced by the fungus—especially ammonia—is toxic to the ants." This is a complete sentence.
Read the part after the blank: "they remove it through a specialized ventilation system built into the nest architecture." This is also a complete sentence (it has a subject "they" and a verb "remove").
So, the blank must connect two independent clauses (two full sentences).
Decide what kind of connector is needed
The meaning shows cause and effect: the waste is toxic, so the ants remove it. That relationship is expressed by the word "consequently."
Because we are connecting two independent clauses with a conjunctive adverb like "consequently," we cannot use just a comma. We need:
- a semicolon or period before the conjunctive adverb, and
- usually a comma after it when it starts the second clause.
Recall the punctuation rule for conjunctive adverbs
Common conjunctive adverbs include "however," "therefore," "consequently," "thus," and "moreover."
When they connect two independent clauses, the standard pattern is:
- first clause
- semicolon
- conjunctive adverb
- comma
- second clause
So we are looking for an answer that follows this pattern with "consequently."
Match the rule to the answer choices
We need punctuation that:
- Puts a semicolon before "consequently" (to correctly join two independent clauses), and
- Puts a comma after "consequently" (because it introduces the second clause).
Choice A, "ants; consequently," gives exactly that structure:
"...is toxic to the ants; consequently, they remove it..."
This correctly connects the two complete sentences and follows Standard English conventions, so the correct answer is "ants; consequently,".