Thiols (R-S-H) Undergo Addition to Alkenes but Only in the Presence

Thiols (R-S-H) undergo addition to alkenes but only in the presence of peroxides. This equation is an example.
$$\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \mathrm { C } = \mathrm { CH } _ { 2 } + \mathrm { RSH } \stackrel { \text { peroxides } } { \longrightarrow } \left( \mathrm { CH } _ { 3 } \right) _ { 2 } \mathrm { CH } - \mathrm { CH } _ { 2 } \mathrm { SR }$$ Which one of these is a reactive intermediate in this reaction?
(a) $\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \mathrm { C } - \dot { \mathrm { C } } \mathrm { H } _ { 2 } - \mathrm { SR }$
(b)

(c) $\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \stackrel { + } { \mathrm { C } } - \mathrm { CH } _ { 2 } - \mathrm { SR }$

(d) $\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \dot { \mathrm { C } } - \mathrm { CH } _ { 2 } - \mathrm { SR }$

(e)


(f) $\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \dot { \mathrm { C } } - \mathrm { CH } _ { 2 } - \mathrm { SH }$

A) compound (a)
B) compound (b)
C) compound (c)
D) compound (d)
E) compound (e) f.
compound (f)