My Spanish teacher <u>who wears flowers in her hair</u> is very pretty . The underlined pattern is the adjective clause. It is a clause because it is a sentence; it has got a subject : <em>who</em>, and a predicate: <em>wears flowers in her hair. </em>This clause works as an adjective because it qualifies the subject of the main sentence : <em>My Spanish teacher</em>. The adjective clause gives some specific information about the Spanish teacher.
Please include the passage and the statements, if the question is multiple choice.
If you accept either C or D as the correct revision then you have to accept both of them. Hence the best way to treat the sentence is to ignore both of them.
B is not correct either. You can over punctuate.
That leaves A.
Sometimes the right answer to many things is to do nothing. My dad used to say "Don't fix what isn't broke."
A is the answer <<<<<