The Ariane 5 satellite launch vehicle failed because:

A. a faulty on-board computer caused the other computers in the network to crash repeatedly.

B. a bad sensor fed faulty information into the flight control computer, causing it to fail.

C. the rocket's on-board computer sent back faulty information to ground control, causing the human controllers to destroy the rocket.

D. code that worked correctly on the Ariane 4 failed on the Ariane 5.

is it D

http://www.google.com/search?q=Ariane+5+satellite+launch&oq=Ariane+5+satellite+launch&aqs=chrome..69i57.2707j0j7&sourceid=chrome&es_sm=122&ie=UTF-8#q=ariane+5+launch+failure

If we here at Jiskha have to Google these topics for you, then I have to ask why you don't use Google yourself in the first place?

Yes, the correct answer is D. The Ariane 5 satellite launch vehicle failed because the code that worked correctly on the previous version, Ariane 4, failed on the Ariane 5. The failure occurred due to an unhandled exception related to a software bug in the inertial reference system. This bug caused a data conversion error, as a 64-bit floating-point number was attempted to be converted into a 16-bit signed integer, which resulted in an overflow. As a result, the guidance system failed and the rocket veered off course, leading to a self-destruct command being issued by ground control. This incident, which took place in 1996, is a well-known example of a software engineering failure with severe consequences.