Which word in the sentence is a direct object? did she teach her dog and cat those amazing tricks?
a. tricks
b. she
c. dog
d. cat

Tricks

Subject: she
Verb: did teach -- active voice, past tense, simple aspect, interrogative mode
Indirect object: dog and cat
Direct object: tricks

The word "her" modifies the compound object "dog and cat". The words "amazing" and "those" modify the object "tricks". The word "and", of course, is a correlating conjunction.

99, multiply all the sides