A. were not required to provide advice pertaining to hotels and entertainment when they were organizing travel packages, but many do so
--> The sentence refers to something that happens but "were" in the beginning leads to the past tense, a completed action
B. are not required to provide advice pertaining to hotels and entertainment when they organize travel packages, but many do so
--> Correct
C. were not required for providing hotel and entertainment advice when they organized travel packages, but many do it
--> The sentence refers to something that happens but "were" in the beginning leads to the past tense, a completed action. "do it" is incorrect as it would not refer to an action.
D. were not required that they provide advice pertaining to hotels and entertainment when they organized travel packages, but many had been doing so
--> Isn't particularly incorrect. But the original sentence refers to a present context and we have an answer that conforms to that.
E. had not had the requirement for them to provide advice pertaining to hotels and entertainment when they organize travel packages, but many do it
--> "had not had" is an awkward construction. The sentence starts with past perfect and goes on to the present. Faulty construction.
Option B