Consider the two symbolic equations below.
(1) Al³⁺ + 3 e⁻ → Al
(2) Zn → Zn²⁺ + 2 e⁻
When the two equations are combined to obtain a single balanced reaction, what is the smallest whole-number coefficient that must be placed in front of Al³⁺ in equation (1)?
(a) 6
(b) 1
(c) 2
(d) 3