A balloon with mass 'm' is descending down with an acceleration 'a' (where a < g). How much mass should be removed from it so that it starts moving up with an acceleration 'a' ?

Question

( A ) $\frac{ma}{g-a}$
( B ) $\frac{2ma}{g-a}$
( C ) $\frac{2ma}{g+a}$
( D ) $\frac{ma}{g+a}$