Answer:
D. its; it's
Step-by-step explanation:
A sentence can be defined as a group of words that comprises of both a subject and predicate used to convey a logical information. Sentences are classified into four (4) main categories and these includes;
I. Simple sentence.
II. Compound sentence.
III. Complex sentence.
IV. Compound-Complex sentence.
A homophone can be defined as two or more words having the same pronunciation but different in spellings, origin or meaning.
In English language, its is simply a possessive determiner used to depict or show that something refers or belongs to someone (something), as the case may be.
On the other hand, it's is a contraction (abbreviation) of "it is" or "it has" and it describes an action performed by a subject.
Hence, the proper use of "it's" and "its" in the sentence would be;
Each of our dogs curls up in its own bed when it's sleeping.
Note: its describes the ownership of the bed by each dog while it's indicates an action performed by the dog i.e sleeping.