An apostrophe question tests whether a noun shows ownership and how many owners there are. Read past the blank and any describing words, then flip the nouns with of: does that keep the meaning? If not, use no apostrophe. If it does, one owner takes ’s, while several owners ending in s take an apostrophe after the s. Count the owners, not the things they own, because several things can belong to one owner.
Hints
- Hint 1
Read past upper to the noun it describes, and ask whether the heart owns that thing.
- Hint 2
Count the owners, not their chambers. Which words at the start of the passage tell you how many hearts are being described?
Step-by-step
Test ownership, then count the owners
Step 1Find what belongs to the heart
The words upper chambers follow the blank, and upper describes the noun chambers. Does the heart own those chambers? Let's try the of test by flipping the nouns: the upper chambers of the heart. That's what the sentence means, so the heart needs an apostrophe to show ownership. We still need to place that apostrophe, which depends on how many hearts the passage names.
- Step 2
Count the hearts and place the apostrophe
How many owners are there? A human heart has four chambers names one heart and several chambers, so one heart owns all four chambers. One owner takes ’s, while several owners whose plural ends in s take an apostrophe after the s. We add ’s to heart because the chambers belong to one heart, giving heart’s. Choice D.