Answer: b. It only arrest growth of vegetative cells
Explanation: An antimicrobial agent is a substance that kills o control the growth of microorganisms, for humans this is very important in medicine or agriculture among others.
This agent should act quickly and being stable that help it to make it cheaper, also should not harm humans or other host of the microbial organisms.
The agent is not useful if only kills vegetative cells because it is not preventing the reproduction of the organism specially in fungi which use sexual reproduction as a backup for asexual cell division, so they will keep spreading across the host.