Answer:
The answer is letter E.
Step-by-step explanation:
Letter A is incorrect because she didn't achieve those goals as the former chair, she achieved when she was an active member of the board.
Letter B is incorrect because there is a long noun modifier the former chair, modifying another noun, so we have an ambiguity here.
Letter C is incorrect because without the article THE, to refer to a person the sentence loses its meaning. We need the article to identify Joan.
Letter D is incorrect because if we use she was, two independent clauses wil be separated by a comma and this is gramatically incorrect.
Letter E. Is the correct one because the preposition as can be used to express a time period, which is the intention of the sentence.