Final answer:
You need to apply for a variance when prepping food by smoking due to food safety concerns. Filtration does not kill microbes but physically removes them from samples using a membrane.
Step-by-step explanation:
The operation preps food by smoking if you need to apply for a variance. This is because smoking food as a way to preserve or flavor it can pose risks such as the potential for growth of botulism-causing bacteria.
Variance in this context is a regulatory measure that allows a food establishment to deviate from standard food code requirements under controlled conditions to ensure food safety.
Out of the options given, filtration is the microbial control method that does not kill microbes or inhibit their growth but instead removes them physically from samples.
Filtration makes use of a physical barrier, typically a membrane with pores small enough to trap microorganisms, while letting the liquid or air containing the microbes pass through.