Consistency models

Client A's write x = 1 returns at t = 10 ms. Client B, on another continent, starts a read of x at t = 12 ms and gets the old value 0. Which model does this history violate?

Client A writes x = 1 and the write returns. Afterwards, client B reads x = 0, then reads x = 1. Every client observes the same overall order. Which is true?

A user who did not write anything reloads a page three times. Their reads return post version 7, then version 5, then version 7. Which guarantee is violated?

Bob reads Alice's question, then posts an answer. Carol's replica shows Bob's answer but not Alice's question. Which is the weakest model this violates?

Which features need a linearizable operation? Select all that apply.