Answer: Option (A) is the correct answer.
Explanation:
An atom contains three sub-atomic particles namely protons, neutrons and electrons.
The nucleus of an atom contains protons and neutrons only. Whereas electrons revolve around the nucleus. Protons are positively charged, neutrons have no charge and electrons are negatively charged.
When an atom is neutral then number of protons equal the number of electrons. Hence, the atom becomes neutral as positive charge is equal to negative charge and thus gets cancelled.
Therefore, a nucleus can be either positively charged or neutral.