A cruise ship is having troubles with buoyancy. What is a reasonable solution

a)Spread the weight of the ship over a greater volume
b)Decrease the volume of the ship
c)Increase the weight of the ship above water
d)Increase the mass of the ship

a)Spread the weight of the ship over a greater volume

Just as a disclaimer...cruise ships never reach anywhere near their capacity weight. Since they're designed as passenger vehicles they have very large safety margins.

a) If you increase the volume of the ship, it displaces more water without changing mass. This means the buoyant force increases and the ship floats better.
b) Your buoyant for will decrease because your ship is displacing less water and has the same mass still.
c) This is irrelevant. The buoyant force doesn't care where the center of gravity for the ship is. The only important factor is how much total water is being displaced.
d) This will only increase the force of gravity without changing the buoyant force.

It's too late to change the ship so I guess there is nothing to do but throw passengers overboard.