Identify the spectator ions in the complete ionic equation:

2K⁺(aq) + S²⁻(aq) + Pb²⁺(aq) + 2NO₃⁻(aq) --> PbS(s) + 2K⁺(aq) + 2NO₃⁻(aq)

a) K⁺ and NO₃⁻
b) S²⁻ and NO₃⁻
c) Pb²⁺ and K⁺
d) Pb²⁺ and S²⁻