I believe it is the pacific ocean as that is the ocean where the Mariana Trench is located, and the Mariana Trench is the deepest place in the Oceans
I believe the answer is C.
It would cause Rain. But a cold front. Fronts are always in relation to moving cold air A cold front is the advancing edge of a cold air mass and a warm front is the retreating edge of a cold mass. If the cold air mass is displacing the warm air front then the cold air is advancing.
Stabilizing a LEG, once it is broken, by using 2 boards extending from the upper thigh to the bottom of the foot is a proper way to help an injured victim in the field.