Final answer:
The reaction between calcium cyanide and sulfur yields calcium sulfide and thiocyanogen, with the primary product being calcium sulfide (CaS).
Step-by-step explanation:
The given chemical reaction is CaCN + 3S → CaS + CNS. In this reaction, a compound of calcium cyanide (CaCN) reacts with sulfur (S) to form calcium sulfide (CaS) and thiocyanogen (CNS). The product of this reaction is, therefore, both 3) CaS and 4) CNS. Since the question asks for the singular 'product', the primary expected answer according to the standard form of the question would be 3) CaS, which is one of the two products formed.