In 1996 the Ariane 5 rocket destroyed itself 37 seconds after launch, from converting a 64-bit float to a 16-bit integer that overflowed. What is the general lesson?

C. That representable range is part of a program's contract

The software was correct, for Ariane 4. A faster rocket produced a velocity outside the 16-bit range, and reuse carried the code across without re-checking its assumptions. Range is part of the contract, and 370 million dollars was the cost of an implicit precondition.