Which image shows the correct way of lining up vectors to add them together?

Image A shows the correct way. You add vectors from the head of one (the arrow-tip) to the tail of another.

the pull of gravity on the rocket decreases

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be