My English literature class was probably my most difficult course and this is because we were required to read twelve novels in six weeks.
My English literature class was probably my most difficult course and this is because we were required to read twelve novels in six weeks.
My English literature class, in which we were required to read twelve novels in six weeks, was probably my most difficult course. This sentence clearly conveys the information without redundancy and maintains a balanced structure by placing the additional information about the reading requirement in a non-restrictive clause within commas.
My English literature class, in which we were required to read twelve novels in six weeks, was probably my most difficult course