Ans 1:
Class : Class 9
I think answers A and B make sense to me, but I unfortunately answered A, which was wrong.
Ans 2:
Class : Class 8
I answered D option which turned out to be incorrect. Instead, the answer was B which is clearly grammatically wrong.
Ans 3:
Class : Class 8
In my opinion, the answer could be either option (A), option (B) or option (D). Both option (A) and option (D) imply that the 'little sister' bought a laptop for herself on her birthday, which is a normal thing to do. Option (B) implies that someone else had bought a laptop for her, as a gift. Thus, all three options are correct. Option (B) is given as the answer based on the stereotype that a 'little sister' is young, which is inaccurate as she can also be old and able to earn her own money, and buy herself gifts.
Ans 5:
Class : Class 9
The question says "My little sister____ a new laptop" Everyone is saying that it will be option BIf we put it in the sentence, it will be "My little sister 'was bought' a new laptop" which makes no sense, literally or grammatically. It don't think it would be option B, instead it should be option D "My little sister 'had bought' a new laptop"
Ans 6:
Class : Class 8
"was bought" is correct in the sense that it was bought for her by someone else, but I feel that "bought" is also correct, implying that she treated herself.