The events are described as:

E1 = age of the insured: 3 age divisions, so n(E1) = 3.

E2 = sex: 2 possibilities, so n(E2) = 2.

E3 = marital status: 2 possibilities, so n(E3) = 2.

Each event is independent, so

n(E) = n(E1) × n(E2) × n(E3) = 3 × 2 × 2 = 12