'A' and 'B' contract that 'A' shall build a house for 'B' at a fixed price. The order in which reciprocal promises are to be performed was not fixed. What shall be the order of performance?
1
A's promise to build the house must be performed before B's promise to pay for the house.
2
B's promise to pay for the house must be performed before A's promise to build the house.
3
A & B should perform their promise simultaneously.
4
None of the above.