On whose writings are the economic policies of the speaker (see below) largely based?" My sole aim is profit. By making a profit I serve the...

Given these options, the only possible correct answer is
B.  This is a statement that could not be based on the ideas of any of these thinkers
other than Adam Smith.

Adam Smith is best known for his
idea of the "invisible hand" of the market.  He says that the economic decisions that
are made in a society must be made by the demands of the market, not by any kind of
governmental policies.  This is very much in line with the last line of the statement
you have given us.

All of the other people that you mention
were more or less opposed to the capitalist system.  All of them were, to one degree or
another, more receptive to socialist ideas.