When I am alone, I hear the footsteps of my friend in my imagination.

When I am alone, I hear the footsteps of my friend in my imagination.

A. The footsteps of my friend heard by me, when I am alone.

B. The footsteps of my friend is heard by me when I am alone.

C. The footsteps of my friend are heard by me when I am alone.

D. The footsteps of my friend was heard by me when I am alone.