Gamma irradiation:.
1. has not been approved for use on food
2. can be used to either sterilize or pasteurize, depending on the dose of radiation
3. leaves some radioactive particles in the treated substance.
4. usually kills by generating heat and denaturing proteins.

Option B, can be used to either sterilize or pasteurize, depending on the dose of radiation

Explanation:

Sterilization by radiation has started since 1895. However, commercial food irradiation plant was installed at Stuttgart, Germany in 1958. In general gamma radiation is used for sterilization purposes which disrupts the sub-atomic particles involved in the formation of the microorganism at an early stage by damaging their genetic material such as DNA or RNA with in their cells. Once the genetic material i.e DNA or RNA is damaged, the cell dies automatically.  

Hence, option B is correct

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.