Question

when an electron moves from a lower to a higher energy level, the electron
absorbs a quantum of energy.
moves closer to the nucleus.
absorbs a continuously variable amount of energy.
always doubles its energy.

Explanation:

According to the Bohr model of the atom, when an electron transitions from a lower energy level to a higher one, it must absorb energy. This energy is in discrete packets called quanta. Moving closer to the nucleus would imply a lower energy level (since electrons in lower - energy orbitals are closer to the nucleus). Energy absorption in atoms is quantized (not continuously variable), and there is no rule that an electron always doubles its energy when moving to a higher level.

Answer:

absorbs a quantum of energy.