Frank Says to Stella,"If You Wash Every Window in My

Multiple Choice

Frank says to Stella,"If you wash every window in my house today,I'll pay you $200." Stella washes 12 of the 20 windows in Frank's house by 2:00 p.m.At this point,________.

A) Frank can revoke his offer to pay Stella the $200 for washing the windows
B) Stella is obligated to finish washing the windows
C) Frank cannot revoke his offer to pay Stella $200 for washing all the windows
D) Frank and Stella have a formal, executed contract