B. Is faster in solids than liquids would be the correct answer because the molecules in solids are much closer and can pass along energy faster and more effectively.
The density is 81.4 g/m3. Before you start plugging numbers into the density formula (D=M/V), you should convert 104 kg to grams, which ends up being 104,000 grams. Then you can plug in the 104,000 grams and 1,278 m3 into the formula. When you divide the mass by the volume, you get a really long decimal, which you can round to 81.4 g/m3, or whatever place your teacher wants you to round to.
It's acquired. Innate means you have it at birth, acquired means you picked it up. Obviously babies can't speak ;) so it's acquired.
Because the specimen is very small with a light microscope
All it does is lets him pull in a more convenient direction to raise the load. It has no effect on the required force.