Answer:
Neither aspects of Dominique are correct.
Step-by-step explanation:
They will not have the same speed before hitting the ground.
The block C has an initial horizontal velocity v₀ₓ , therefore the total ultimate speed before hitting the ground is v = √ v₀ₓ² + vy²
It didn't matter how the blocks were dropped, they all landed at the same time. If any block has an initial vertical velocity it will have a higher end velocity. If Dominique means dropped from the rest then the previous claim is true. It is important how they were dropped.
The Dominique must said : The vertical speed will be the same because of conservation of energy.
The fact is, they all landed at the same time and that is true. And it is important how they are thrown away.
God is with you!!!