An apostrophe question with two nouns tests whether each owns something and how many owners there are. Read through the blank, and test each noun on its own by asking whether it owns the thing named next. You can flip the nouns with of to check that meaning. If it owns something, count the owners: one takes 's, while a plural ending in s takes an apostrophe after the s. A noun that owns nothing needs no apostrophe.
Hints
- Hint 1
The blank belongs to the part of the sentence that says what signals breeding season. Read that whole part, not only the words inside the choices.
- Hint 2
Where does the passage tell you how many birds there are? Use that count when testing the noun that names the birds.
- Hint 3
For the noun naming the sounds, check what follows it. Does it own anything named after it?
Step-by-step
Test ownership, then count owners
Step 1Check who owns the calls
Read the part after the semicolon: the ______ and swooping dives. The choices change gulls and calls, so we need to decide whether each noun owns something, not whether the whole phrase sounds right. Do the gulls own the calls? Skip distinct, which describes the calls, and flip the nouns with of: the distinct calls of the gulls. That matches the sentence’s meaning, so the gulls are owners and gulls needs an apostrophe.
- Step 2
Count the birds
How many birds own those calls? The text says hundreds of Western gulls, so the owners are many birds, not one. To place an apostrophe, count the owners rather than the sounds they make, since one bird could make several calls. A plural noun ending in s shows ownership with an apostrophe after that s, which is what gulls needs here.
- Step 3
Check the calls separately
What comes after calls? The words and swooping dives join the calls to the dives, and together they signal the start of breeding season. The calls don’t own anything here; they’re one of the things that signal breeding season, so calls stays a plain plural, with no apostrophe. That gives us gulls' distinct calls. Choice D.