Answer the following question given this paragraph: Stars shine because of nuclear fusion. Fusion reactions in the Sun's core keep our nearest star burning. Stars are made mostly of hydrogen and helium. Both are very lightweight gases. A star contains so much hydrogen and helium that the weight of these gases is enormous. The pressure at the center of a star is great enough to heat the gases. This causes nuclear fusion reactions. Q: What process, which results because of great pressure at the center of a star, causes stars to shine? A:

Choose your answer from: *gravitational pull; *electric fusion; *energy fusion; *nuclear fusion;
The answer is:
nuclear fusion