Answer:
a condition precedent
Explanation:
The answer is "a condition precedent"
When Josh wishes to buy a property from Antonio where once a gasoline station stood, they included a language in the contract making the purchase contingent on a belief that there are no environmental problems with the property.
The contingency represents a condition precedent that there was a gasoline station once on the land before Josh bought it from Antonio.
Thus the answer is "a condition precedent".
