ROH + TsCl + pyridine ----> R-OTs + Cl:

For the reaction, what is the function of pyridine?
The pyridine is on top of the arrow in the question.

a)Serves as a lewis base, stabilizes transition state.

b)Serves as a cofactor,complexes with the alcohol.

c)Weak base. Proton acceptor for hydroxyl.

d)Catalyst, bonds to Tosyl to increase reactivity.