Correct Answer: (d) backer
Solution:Patron: a person who gives financial or other support to a person, organization, or cause.
Backer: a person, institution, or country that supports someone or something, especially financially.a
Entrepreneur: a person who sets up a business or businesses, taking on financial risks in the hope of profit.
Admirer: a person who has a particular regard for someone or something.
Critique: a detailed analysis and assessment of something, especially a literary, philosophical, or political theory.
Here, 'backer' is thus the nearest in meaning with the given word 'Patron'.