Buying new clothes so that your friends will stop making fun of your old clothes a positive reinforcement or negative reinforcement?

It depends really, if you liked your old clothes better and it was really bothering you with your friend making fun of you so you gave into it, that is negative however if you are comfortable with the new clothes and you are happy that your friend has laid of, then it is positive but don't change yourself for someone else.

c. wright mills's sociological imagination suggest investigating to explain this increase?

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.