Question 232·Easy·Boundaries
Blue whales, the largest animals on Earth, can communicate across entire ocean basins, their low-frequency calls traveling hundreds of miles. Scientists continue to study how these majestic creatures use sound to find mates, navigate, and locate _____
Their vocalizations provide clues about population sizes and migration routes, informing conservation efforts.
Which choice completes the text so that it conforms to the conventions of Standard English?
For boundaries questions, locate the independent clauses and decide whether the blank must (a) join two clauses into one sentence or (b) end a sentence and start a new one. Then eliminate choices that create run-ons, comma splices/incorrect end punctuation, or incorrect semicolon usage. When a coordinating conjunction like "but" connects two independent clauses, look for the comma immediately before it.
Hints
Find the independent clauses
Read the sentence with each option and check whether you have two complete clauses (each could stand as its own sentence) before "Their vocalizations...".
Use the FANBOYS rule
If two independent clauses are joined with a coordinating conjunction like "but," you typically need a comma right before that conjunction.
Check the punctuation right before "Their vocalizations"
The text after the blank must end the sentence correctly so that "Their vocalizations..." begins a new sentence. A comma there would usually signal an error.
Step-by-step Explanation
Identify the structure around the blank
Before the blank, the sentence reads: "Scientists continue to study how these majestic creatures use sound to find mates, navigate, and locate ...".
Each answer choice then adds another complete idea about acoustic tags, and after that the passage continues with a new sentence: "Their vocalizations provide clues...".
So you need the insertion to (1) correctly connect the two ideas and (2) correctly end the sentence before "Their vocalizations...".
Use a correct boundary between two independent clauses
The first part (ending with "food") is an independent clause, and the added part (about acoustic tags revealing complexity) is also an independent clause.
A standard way to join two independent clauses is:
- independent clause, comma + coordinating conjunction (for, and, nor, but, or, yet, so) + independent clause.
Test each option for boundary errors
- A uses a semicolon and then adds the coordinating conjunction "but." On the SAT, a semicolon is used instead of a coordinating conjunction to join two independent clauses.
- B ends the sentence after "food" (which is fine), but it places a comma after "songs," which would incorrectly attach what follows ("Their vocalizations...") to the previous clause.
- C uses "but" to join two independent clauses but omits the comma before "but."
- D uses a comma before "but" and ends with a period after "songs."
Choose the option with correct boundaries
Only option D correctly joins the two independent clauses and cleanly ends the sentence before the next one starts.
Correct answer: food, but only recently have acoustic tags revealed the full complexity of blue whale songs.