To be deductible，the dominant motive for incurring an expense must be（）the relationship to a business activity.

A.to set up rules about the use of pesticides and enforces them all over the country.
B.to make sure any hole that might allow pests to enter a building should be filled.
C.to check that doors and windows are completely closed.

A.To follow state and local health laws.
B.To be carried by employees.
C.To help control pests and help prepare for any inspection.

A.to prevent pests from entering a building from outside.
B.to protect rice and wheat from rain and wind.
C.to block the growth of plants.