What does it mean that energy is quantized?

a. energy cannot be created or destroyed, but can only change from
one form to another.

b. energy exists only in discrete forms, such as kinetic potential, and
chemical.

c. energy does not exist in continuous amounts, but only in set
increments.

d. energy and mass are equivalent, and can change back and forth
between forms.

Quantization is the concept that a physical quantity can have only certain discrete values. ... For example, matter is quantized because it is composed of individual particles that cannot be subdivided; it is not possible to have half an electron. Also, the energy levels of electrons in atoms are quantized...
Rather than continuous waves, light was coming in packets of energy which can be defined with its frequency and planck constant 'h' as we mentioned earlier and said 'so, the energy is quantized'. In the atomic world, energies are also quantized. This means it can have only certain values.

Abecause its more effective

Iwould sure like to answer your question but i honestly just don’t know