If you were asked to describe the personality of your best friend, and you said that she was optimistic, reserved, and friendly, you would be using the approach.

Trait approach

Explanation:

Trait approach is the technique that is used for studying and evaluating about the personality of an individual based on the traits displayed by him/her. Behavioral pattern, habits, emotions, feelings, views etc are assessed in form of trait markers for determining the personality of particular person.

According to the question, if personality of the friend is described as reserved, cheerful and friendly by a person then personality traits are being mentioned .Thus, the approach used for defining friend's personality is trait approach.

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.

i honestly have no idea