Final answer:
Technician A is correct that stretch fit belts use a spring-loaded tensioner to stay tight. Technician B is incorrect; a bottom-out belt usually needs replacement, not tightening.
Step-by-step explanation:
The question is regarding automobile belt systems and their maintenance. On one hand, Technician A says that stretch fit belts use a spring-loaded tensioner to keep them tight, which is correct. These belts are designed to maintain tension without manual adjustments. On the other hand, Technician B suggests that a bottom-out belt, which is a belt that has no more room for adjustment because it has stretched to its limit, can be fixed by tightening it. This is not correct because once a belt has bottomed out, it cannot simply be tightened; it typically needs to be replaced.