The correct option is A was, is, will be
Tense is used to provide more information about an action ( its time, completeness, etc.). Option B)was, is, will be is correct as the principal cause uses the simple present tense and therefore, the subordinate clause can use simple present, simple past, simple future, or present perfect tense and the sentence talks about the past first (in the subordinate clause), present second, and future later. The other options are wrong as the past is about the time that is gone, the present is about the present state, and the future is about what will happen in the future. The correct answer is B)was, is, will be.