THe Q seemz OK ! Why did you think it to be poor !
Seems poor to me.
It is not (E), because the second does not try to refute the first conclusion. the first conclusion does not say that TV is the only factor...., but an important factor.
However, by elimination , i'll choose (B). I am not strong on (B) because '...a similar expt was conducted' meaning that we are refering to the same social group (children, maybe of same ages, etc)