A punctuation question with two marks in a list tests whether you can tell breaks between items from marks inside them. Read the whole list and find the job of each mark. Commas separate simple list items; semicolons separate items containing commas; a colon follows a complete clause to introduce a list or explanation. Then check where each description begins: extra facts starting with which take a comma, so keep those words with what they describe.
Hints
- Hint 1
Start at the colon that introduces the safeguards. Identify each safeguard and the words that describe it.
- Hint 2
Look near the end of the sentence for the mark between whole list items. How does its job differ from the commas inside those items?
- Hint 3
The words after the blank start with which. Check what they describe and how the other descriptions begin.
Step-by-step
Separate list items from descriptions
Step 1Find each punctuation job
The colon in a separate suite of safeguards: introduces a list, so we're choosing punctuation in that list. What belongs in it? The sentence names filtered water, climate-controlled chambers, and sterilized feeding tools, with describing words after each one. The choices change a mark after stream and another after chambers, and one ends the water item while the other introduces the chambers' description.
- Step 2
Match the marks between list items
What mark does this list already use between safeguards? In humidity; and sterilized feeding tools, which, the semicolon ends the chambers item, while the comma starts the tools' description. When any list item has a comma, semicolons separate the whole items, so let's use the same mark: the water item needs a semicolon after stream. A comma after stream doesn't match the list's pattern. A colon there would make the chambers and tools an explanation of the water, not more safeguards.
- Step 3
Attach the chambers' description
After climate-controlled chambers, read which reproduce seasonal changes in temperature and humidity and ask what those words describe. They add a fact about the chambers, so the which part takes a comma before it, matching sterilized feeding tools, which reduce later in the list. A semicolon after chambers would split the chambers from their own description, so we need the version with a semicolon after stream and a comma after climate-controlled chambers. Choice D.