Answer the question

Signs in many stores and restaurants warn that microwaves are in use. What is the main reason for this warning?
OPT:
--Some people do not like food cooked in microwave ovens.
--Microwaves sometimes affect people's sense of sight.
--Microwaves sometimes cause hair or teeth to fall out.
--Some people have pacemakers that may be affected by microwaves.
Some people have pacemakers that may be affected by microwaves.