Question

HELP!! I think its A but I'm not sure.
Choose the one that is a grammatically correct complete sentence.
A. At the back of the classroom, Nina sat with her arms crossed, glaring at her teacher, Mr. Beane.
B. John is a good-natured roommate, however, he does lose his temper once in a while.
C. Not realizing that the student was a budding genius.
D. Traffic jams in major cities have gotten out of hand car pools should be mandatory.

Answer 1

I think the most grammatically correct answer is actually B. Correct me if I am wrong.

Answer 2

A is the grammatically correct sentence.

Here's Why:

B consists of two independent clauses.

C is a fragment sentence

D is a run-on sentence.

Hope this helps!