Delta is currently trading for $20/share, while Southwest is currently trading for $40/share; assume neither stock pays a dividend. If an option to exchange 3 shares of Delta for a share of Southwest in 2 years currently costs at 0.5 shares of Delta stock, what would an option to exchange 1/3 share of Southwest for a share of Delta in 2 years cost in shares of Southwest?

A. 1/5 of a share

B. 1/4 of a share

C. 1/3 of a share

D. 1/2 of a share

E. 2/5 of a share