Question

what causes light to be emitted by an atom?
electrons jumping from an energy level close to the nucleus to one farther from the nucleus
all of the electrons in the atom dropping to the innermost energy level
electrons staying in their energy level but moving much quicker
electrons dropping from one energy level to an energy level closer to the nucleus

Explanation:

When electrons move from a higher - energy outer level to a lower - energy inner level, they release energy in the form of light (photons). This is based on the principles of quantum mechanics in atomic physics.

Answer:

Electrons dropping from one energy level to an energy level closer to the nucleus