Which of the following equations represents a substitution reaction?

A. C2H10(g) + CI2(g) → C4H9CI(g) + HCI(g)
B. C2H4(g) + HCI (g) → C2H5 CI(l)
C. C2H2(g) + 2H2(g) → C2H6(g)
D. C3H4(g) + 402(g) → 3CO2(g) + 2H2O(g)

Correct Answer: Option A

A. C2H10(g) + CI2(g) → C4H9CI(g) + HCI(g)