Concept:Use the past perfect tense for the earlier of two past actions.
Explanation:The sentence describes two events in the past: meeting a friend and shifting to Hyderabad.
The shifting happened later, so “shifted” is in simple past tense.
The meeting happened before the shifting, so it must be in past perfect tense: “had met”.
Using “has met” (present perfect) is incorrect because the entire context is past.
Hence, the error is in part (a).
All other parts are correct.
Answer:(a)