The form of e$-$commerce that is the largest in terms of sales dollar volume is $$ e$-$commerce.

A$.$ business$-$to$-$consumer $($B$2$C$)$

B$.$ business$-$to$-$business $($B$2$B$)$

C$.$ consumer$-$to$-$organization $(C2O)$

D$.$ consumer$-$to$-$business $(C2B)$

E$.$ consumer$-$to$-$consumer $($C$2$C$)$