The solidity of bridge piers built on pilings depends largely on how deep the pilings are driven. Prior to 1700, pilings were driven to "refusal, " that is, to the point at which they refused to go any deeper. In a 1588 inquiry into the solidity of piers for Venice' s Rialto Bridge, it was determined that the bridge' s builder, Antonio Da Ponte, had met the contemporary standard for refusal: he had caused the pilings to be driven until additional penetration into the ground was no greater than two inches after twenty-four hammer blows. Which one of the following can properly be inferred from the passage?
A: After 1588, no bridges were built on pilings that were driven to the point of refusal.
B: Da Ponte's standard of refusal was less strict than that of other bridge builders of his day.
C: The Rialto Bridge was built on unsafe pilings.
D: It is possible that the pilings of the Rialto Bridge could have been driven deeper even after the standard of refusal had been met.
Choose A, B, C or D as your solution.
D