The given sentence consists of two parallel sentences with no conjunction between them. In such a case, a semi colon is used to join them.
The second half of the sentence consists of two dependent elements but the conjunction is left out. So, a comma must be used between the elements to separate them.
Thus, the correct will be Option A.
An em dash is used when the sentence calls for a more emphatic tone, which is not the case in the given sentence.