This is not your book, it is …

Analyze the question: The sentence "This is not your book, it is __" needs a word showing that the book belongs to someone named Andrew. That calls for the possessive form of the noun.

Concept: possessive nouns

• For a singular noun, add apostrophe + s ('s) to show ownership: Andrew's book, the teacher's pen.
• For plural nouns ending in -s, add only an apostrophe: the students' books.
• Without an apostrophe, a word ending in -s is just a plural, not a possessive.

Step by step:

1. The sentence means "it is Andrew's (book)", so the book belongs to Andrew.
2. A. Andrew is just the name. It does not show ownership, and "it is Andrew" would mean the book is a person.
3. B. Andrews is a plural or a different surname. It has no apostrophe, so it shows no possession.
4. C. Andrew's is the singular possessive. It fits the sentence and is correct.
5. D. Andrews' would be the possessive of a name that already ends in s (such as the Andrews family), but the name here is Andrew.

Answer: C. Andrew's

Exam tip: Ask yourself, "Does this word show that something belongs to someone?" If it does, look for an apostrophe. Then check whether the owner is singular (add 's) or plural (add just ').