Technically you’re right. If that one sentence is all the info you are given, there’s no way you could make an assertion as to what would happen…largely because “an improvement in the technology for the production of computers” is so ambiguous it could mean just about anything…and you’re right, that anything doesn’t necessarily have to lower production cost. Hell I could say “an improvement in technology” was made if it was made a more attractive color…or if it was coated with sweet smelling perfume so that any workers nearby got a pleasant oder.
Of course if you had a stickler professor and made assumptions as to what “an improvement in the technology” is/does, and answered “a”, you’d be marked wrong because that enough information isn’t given to make that assertion.
But here you have a case of a professor not being specific and expecting you to make the same assumption errors that he does.
Such is life in the education system.