Question

the number of protons in an atom
○ atomic mass
○ atomic number

the subatomic particle labeled \o\ is the

Explanation:

First Sub - Question (The number of protons in an atom)

The atomic number of an atom is defined as the number of protons in its nucleus. Atomic mass is the sum of protons and neutrons in the nucleus. So the correct option related to the number of protons is atomic number.

In a typical atomic model diagram: A is usually protons/neutrons (nucleus), B is electrons (orbiting), D (assuming the diagram has D as an electron - like particle orbiting or a subatomic particle in the electron cloud region) - electrons are the subatomic particles that orbit the nucleus. If D is in the electron cloud (orbital) region, it's an electron. But since the diagram's labels: C is likely nucleus (protons/neutrons), A is protons/neutrons, B and D (if D is an electron) - electrons are negatively charged and orbit the nucleus. So the subatomic particle labeled D is an electron (assuming standard atomic model where electrons are in the electron cloud around the nucleus).

Answer:

atomic number (the option with "atomic number" text)

Second Sub - Question (The subatomic particle labeled "D")