Answer:
B. Cleaning the room.
Step-by-step explanation:
This is a sentence fragment because it doesn't have a subject (nor a verb).
It has a part of a verb (cleaning) that needs a passive verb such as "am" or "was" (am cleaning or was cleaning).
Just for practice, let's eliminate the other choices.
A. has both a subject (the table) and a verb (was)
C. has both a subject (we) and a verb (shook)
D. has both a subject (he) and a verb (prayed)
E. has both a subject (he) and a verb (took)
Hope this helps!