I believe that metal detectors are a necessary security feature. They should be installed in all public buildings to keep people safe. It is not always possible to know if someone is dangerous by looking at them. By using metal detectors, however, we can keep those who may be carrying concealed weapons away from innocent people.

What is the main point of the article writer's argument?
A.
Metal detectors do not always work and are not reliable.
B.
There should be more security officers in public places.
C.
People should not be allowed to carry weapons in public.
D.
Metal detectors in public buildings help keep people safe.