The correct option is
B she had been
While changing the speech from direct to reported speech, the tense
changes one tense back. For example, if the direct speech is in present
tense (and the reporting verb is in the past tense) then the
indirect/reported speech will be in past tense.
Also, when the speech is indirect, the point of narrative also changes (from I to she/he and from my to his/her).
Option B: The
given sentence is in the present perfect tense "have you been". Hence the reported speech will be in the past perfect tense 'had been'.
Also, the question form changes to statement form while reporting the speech: from 'have you been' to 'she had been'.
So, option B is correct.
Option A: 'She was' is in the simple past tense, whereas the direct speech is in present perfect. So, it should be in past perfect tense.
Option C: Similarly, 'was she' is also in simple past tense. The only difference is that it's in interrogative form ('she was' is in statement form).
Option
D: 'Had she been' is in the interrogative form whereas the reported speech is a declarative statement.
Hence options A, C and D are incorrect.