PLEASE HELP WILL MARK BRAINLIEST SCIENCE!! What best explains the source of light energy and heat energy produced by a star?

A. Dense metals, such as iron, explode in the core of a star.
B. Explosions from a nearby supernova provide fuel to the star.
C. Nuclear reactions involving the fusion of atoms occur in the core of a star.
D. High-energy radiation from nearby stars penetrate the core of a star.

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".

What accounts for an increase in the temperature of a gas that is kept at constant volume? a. energy has been removed as heat from the gas. b. energy has been added as heat to the gas. c. energy has been removed as work done by the gas. d. energy has been added as work done by the gas.