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Under basic timestamp ordering, transaction T's write of item Q is rejected (T aborts) if
ATS(T) > W-timestamp(Q)
BT holds no shared lock on Q
CTS(T) < R-timestamp(Q) or TS(T) < W-timestamp(Q)
DQ is currently being read by any other transaction
Answer & Solution
Correct answer: C. TS(T) < R-timestamp(Q) or TS(T) < W-timestamp(Q)
Write rule: abort T if its timestamp is OLDER than the R-timestamp (a newer T already read what T would have produced) OR older than the W-timestamp (a newer T already wrote a newer value). Larger TS means newer, which is fine. The protocol is lock-free, so option B doesn't apply.
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