Question

1. which sentences use apostrophes correctly? the cats tail is fluffy. the dogs collar is red. the students desks were in rows. its color is blue.

Explanation:

1. In "The cats’ tail is fluffy", the apostrophe should be after the "s" in "cats" since it's a plural possessive, it should be "The cats' tail is fluffy".
2. "The dog's collar is red" uses the apostrophe correctly to show singular possession.
3. "The students’ desks were in rows" uses the apostrophe correctly for plural possessive.
4. "Its’ color is blue" is incorrect. The correct form for the possessive of "it" is "its" without an apostrophe, and "it's" is a contraction of "it is".

Answer:

The dog's collar is red.
The students’ desks were in rows.