Identify which one of the following sentences contains an unnecessary comma. Please correct the error and explain why the correction is necessary.

A. I must have been completely absorbed in my work, because I totally forgot about the meeting.
B. Because I became completely absorbed in my work, I totally forgot about the meeting.

3 answers

A. has an unnecessary comma.

This site explains this incorrect comma usage.
http://owl.english.purdue.edu/owl/resource/607/02/
Thank you Ms. Sue! =)
You're welcome, Yonaa.