The schedule written in the tabular form:
T1 |
T2 |
R(A) |
|
|
R(B) |
|
W(A) |
W(A) |
|
In Thomas' write rule, we "ignore the outdated updates".
Since T1 started execution first, so, the W1(A) (in the last row), is an outdated updated. This will be ignored in Thomas' write rule. But in the basic timestamp protocol, this will cause T1 to roll back.
So, correct option is (B)