Answer:
d. One more neutron
Explanation:
Phosphorus-32 is known as a radioactive isotope of the phosphorus element. The nucleus of this isotope has 15 protons and 17 neutrons.
There is also Phosphorus-31 which is the most common isotope of phosphorus. This isotope has at its core 15 protons and 16 neutrons.
Therefore, the difference between them is one neutron more than the other.
