Samples of different materials, A and B, have the same mass, but the sample of A is higher in density. Which statement could explain why this is so?

A. The particles that make up material B have more mass than the
particles that make up material A.
B. The particles that make up material A have more mass than the
particles that make up material B.
C. The sample of material A has greater volume than the sample of
material B.
D. The particles that make up material B are more closely packed
together than the particles that make up material A.

Will you chech and finish these for me, because i am stumped with them.

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 790 n/m. it is initially at rest on an inclined plane that is at an angle of 28 degrees with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is k = 0.14. in the initial position, where the spring is compressed by a distance of a = 0.18 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

If a balloon is taken outside on a very cold day, what will occur?