Formation of Toluene by Friedel-Crafts Reaction:
The Friedel-Crafts reaction is a commonly used organic reaction to introduce alkyl or acyl groups onto an aromatic ring. In the case of toluene formation, the reactants used in the presence of anhydrous AlCl3 are C6H6 (benzene) and CH3Cl (methyl chloride).

Reaction:
C6H6 + CH3Cl → C6H5CH3 + HCl
(benzene) (methyl chloride) (toluene) (hydrochloric acid)

Explanation:
The Friedel-Crafts reaction involves the use of a Lewis acid catalyst, typically anhydrous aluminum chloride (AlCl3). The catalyst facilitates the formation of a carbocation intermediate, which subsequently reacts with the aromatic ring to introduce the desired alkyl or acyl group.

In the given options, only option 'C' contains the required reactants for the formation of toluene. Let's understand why the other options are incorrect:

a) C2H2 and CCl4:
- Acetylene (C2H2) and carbon tetrachloride (CCl4) are not suitable reactants for the Friedel-Crafts reaction to form toluene.
- Acetylene does not have a suitable functional group to react with benzene, and carbon tetrachloride is not a reactive compound in this context.

b) CH4 and CaCN2:
- Methane (CH4) and calcium cyanamide (CaCN2) are also not suitable reactants for the Friedel-Crafts reaction.
- Methane is an alkane and does not have a reactive functional group for the reaction.
- Calcium cyanamide is a compound used in the production of fertilizers and does not participate in Friedel-Crafts reactions.

d) C2H5OH and Zn:
- Ethanol (C2H5OH) and zinc (Zn) are not suitable reactants for the formation of toluene.
- Ethanol does not have a reactive functional group for the Friedel-Crafts reaction, and zinc is not involved in this type of reaction.

Therefore, the correct answer is option 'C' which contains the reactants benzene (C6H6) and methyl chloride (CH3Cl) that can undergo the Friedel-Crafts reaction to form toluene.