What do elements in the first two columns of the periodic table have in common?
a.) they have two valence electrons
b.) they tend to lose electrons to gain stability
c.) they react strongly with the alkali metals
d.) they do not react with halogens

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

They are all solids.