30. On September 1, 2020 S promised to sell her land to B for P100,000 if B will pass Oblicon this semester. Which of the following is false?*

(A) From September to December 2020 S remains to be the owner because the condition is not yet fulfilled.

(B) If in December 2020 B passed the board exam, she shall become the owner, after payment and delivery; the effect shall retroact to September 2020.

(C) If on November 30, 2020 S sold the land to X, the sale is valid because B has not yet fulfilled the condition.

(D) If one year after the promise was made S sold the land to X, the sale is valid whether or not B passes the examination in December 2020.

Brief explanation will do, thanks!