The Sun's gravity pulls the planets in orbit around it, and some planets pull moons in orbit around them. The center of the gravity well is the Sun, and the coins or marbles are a model of the planets. The closer the planet is to the Sun, the greater the pull of the Sun's gravity, and the faster the planet orbits.
The sun's gravity pulls the planet toward the sun, which changes the straight line of direction into a curve. This keeps the planet moving in an orbit around the sun. Because of the sun's gravitational pull, all the planets in our solar system orbit around it.
It should be option (A) because conduction is the transfer of heat energy from one place to another by vibrations/motion of the molecules. I hoped I helped.
The masses are always equal. Since matter can not be created nor destroyed, you will have the same amount of mass as you did before the reaction as you do after.
