An aeroplane flying at a constant speed releases a food-packet for flood victims. As the packet drops away from the aeroplane, 

it will always be vertically below the aeroplane only if the aeroplane was flying at an angle of  ${45}^0$ to the horizontal

it will always be vertically below the aeroplane only if the aeroplane was flying horizontally.

it will gradually fall behind the aeroplane if the aeroplane was flying horizontally

it will always be vertically below the aeroplane as seen by the pilot of the aeroplane