Wally Owns 200 Acres of Land

Wally owns 200 acres of land.Wally offers to sell the land to Robert for $1,500 per acre.Robert replies that he does not need 200 acres of land but would like to buy 40 acres at $1,500 per acre.Wally agrees to sell but does not identify which 40 acres.Later,Wally refuses to sell any land to Robert.What is the result?

A) Robert wins;this is an enforceable contract with complete and definite terms.
B) Robert wins;the UCC will decide which 40 acres are to be sold.
C) Wally wins;the original offer was not intended to be an offer but merely an invitation to negotiate.
D) Wally wins;this agreement is too indefinite since it does not identify which 40 acres are to be sold.