A bomber flying horizontally with constant speed releases a bomb from an aeroplane.
a) The path of bomb as seen by the observer on the ground is parabola
b) The path of the bomb as seen by a pilot is a straight line.
c) The path of the aeroplane with respect to bomb is a straight line
d) The path of the bomb as seen by pilot observed as parabola.

Horizontal component of the bomb relative to an observer on the ground is equal to the velocity of the bomber which is in horizontal direction. The path of the bomb will be same as a horizontal projection which is a parabola.

Horizontal component of velocity of the bomb relative to the pilot of the bomber is zero. The path of the bomb as seen by a pilot and the path of the aeroplane with respect to the bomb is a straight line.