Quinn Promises to Sell His Recreational Vehicle (RV)to Sid,who Builds

Multiple Choice

Quinn promises to sell his recreational vehicle (RV) to Sid,who builds a structure behind his house in which to keep it.Quinn's later attempt to renege on the promise is

A) effective if Quinn did not ask Sid to build anything.
B) effective if Quinn wants to sell the RV to someone else.
C) not effective if Sid cannot obtain a similar RV for a similar price.
D) not effective if Sid detrimentally relied on Quinn's promise.