Chemistry Reaction Mechanism of Cl2 and CHCl3

[i_love_science]

Homework Statement

Which response identifies the intermediate(s) in the following mechanism?
Cl2 -> 2 Cl (fast)
Cl + CHCl3 -> CCl3 + HCl (slow)
CCl3 + Cl -> CCl4 (fast)

A) Cl
B) CCl3
C) CHCl3
D) Both Cl and CHCl3

Relevant Equations

reaction mechanism

I think the answer is both A) Cl and B) CCl3, since both are produced and used up. The correct solution is only A). Could anyone explain why? Thanks.

 

[docnet]

Cl is produced quickly by
$$Cl_2\rightarrow 2Cl$$
and consumed slowly by
$$Cl+CHCl_3\rightarrow CCl_3+HCl$$
On the other hand, $CCl3$ is produced slowly and consumed quickly.

IMO both A) and B) are intermediates, but this problem uses a different logic.