Tell me if it's right.
3, which of these pronouns is third person plural posessive?
a. who
b. that
c. they
d. theirs
4, which kind of adjective is used most frequently in ordinary speech or writing?
a. common
b. proper
c. demonstrative
d. article
5, a noun that completes an action is called a/an
a. complement.
b. object.
c. subject.
d. predicate.

The correct answers to the questions are:

3. D. Theirs - This is the third person plural possessive.
4. A. Common - This is the kind of adjective that is used most frequently in ordinary speech or writing.
5. B. object - This is what a noun that completes an action is called. 

Thank you for posting your question. I hope that this answer helped you. Let me know if you need more help. 

Not b or c so that leaves you with a or d. a is the better choice.

Where is the visual?