Alpha and Beta made a written contract pursuant to which Alpha promised to convey a specified apartment house to Beta in return for Beta's promise (1) to convey a 100-acre farm to Alpha and (2) to pay Alpha $1,000 in cash six months after the exchange of the apartment house and the farm. The contract contained the following provision: "It is understood and agreed that Beta's obligation to pay the $1,000 six months after the exchange of the apartment house and the farm shall be voided if Alpha has not, within three months after the aforesaid exchange, removed the existing shed in the parking area in the rear of the said apartment house.""Alpha's removal of the shed from the parking area of the apartment house is
a condition subsequent in form but precedent in substance to Beta's duty to pay the $1,000.  a condition precedent in form but subsequent in substance to Beta's duty to pay the $1,000.  a condition subsequent to Beta's duty to pay the $1,000. 67  not a condition, either precedent or subsequent, to Beta's duty to pay the $1,000
Question: Alpha and Beta made a written contract pursuant to which Alpha promised to convey a specified apartment house to Beta in return for Beta's promise (1) to convey a 100-acre farm to Alpha and (2) to pay Alpha $1,000 in cash six months after the exchange of the apartment house and the farm. The contract contained the following provision: "It is understood and agreed that Beta's obligation to pay the $1,000 six months after the exchange of the apartment house and the farm shall be voided if Alpha has not, within three months after the aforesaid exchange, removed the existing shed in the parking area in the rear of the said apartment house.""Alpha's removal of the shed from the parking area of the apartment house is
A. a condition subsequent in form but precedent in substance to Beta's duty to pay the $1,000. 
B. a condition precedent in form but subsequent in substance to Beta's duty to pay the $1,000. 
C. a condition subsequent to Beta's duty to pay the $1,000. 67 
D. not a condition, either precedent or subsequent, to Beta's duty to pay the $1,000
Answer: