A, B, C, D, E, F and G each scored a different marks in an exam and all marks were integers. Only three people scored more than F. Only G scored less than B. More than three people scored between G and D. C scored less than E and no one scored between C and E. If E scored 90, F scored 84 and the second lowest score was 71, which of the following may be the possible score of A?

Let the arrangement be as follows:

__ > __ > __ > __ > __ > __ > __

It is given that only three people scored more than F so F should be at fourth position from left.

__ > __ > __ > F > __ > __ > __ 

Only G scored less than B. Thus B and G should be at second last and last position respectively.

__ > __ > __ > F > __ > B > G 

C scored less than E and there is no one in between C and E. So the pair will be E > C. Also there are more than three people between G and D. Thus D can be either at first position or second position. If D is at second position, there would be no place to fit the pair (E > C). Thus D is at first position and E,C are at second and third positions respectively. The remaining position will be occupied by A.

D > E > C > F > A > B > G.

F scored 84 and second lowest score (B) was 71.

A is between F and B. Thus A's score should be between 84 and 71. Only option 79 is the suitable value.

Thus option B is the correct choice.