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