How does an ion differ from an electrically-neutral atom?
a) there are a different number of protons in an ion compared to a neutral atom. b) there are a different number of electrons in an ion compared to a neutral atom. c) there a different number of neutrons in an ion compared to a neutral atom.
d) there are no differences in subatomic particles.

B) There are a different number of electrons in an ion compared to a neutral atom.  

Explanation:

An ion is an atom that has lost or gained electrons. For example, a sodium ion is formed when a sodium atom loses an electron.

A) is wrong. Atoms that contain different numbers of protons are different elements.

C) is wrong. Atoms that contain different numbers of neutrons are isotopes.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

Thermohaline circulation and gyres