Answer:
A. This apple pie was baked for an hour.
C. What kind of apples were used in this apple pie?
D. Erin baked this apple pie.
Step-by-step explanation:
Sentences in the active voice always use this formula:
Subject + Verb + Object
A. This apple pie was baked for an hour.
Subject + Verb + Object
Apple pie + baked + an hour
B. Pippin apples were used for this apple pie.
Object + Verb + Subject
Pippin apples + used + apple pie
C. What kind of apples were used in this apple pie?
Subject + Verb + Object
Kind of apples + used + apple pie
D. Erin baked this apple pie.
Subject + Verb + Object
Erin + baked + apple pie
Therefore, sentences A, C, and D are written in active voice.