B1
The minimum amount of something is the smallest amount that is allowed, needed, or possible.
Dictionary examples:
The minimum grade to pass this class is 'better than the teacher'. (0.0)
The minimum requirement for this job is 'ability to breathe'. (0.0)
The minimum height for this rollercoaster is 'taller than the ticket seller'. (0.0)
Eighteen is the minimum age for entering most nightclubs. (28.7)
That's the minimum degree required to teach English in most language schools. (32.3)
There is a minimum charge of $5 for postage. (54.2)