The correct answer is option 2 - Rousseau.
Jean-Jacques Rousseau is the philosopher who gave the statement "Man is born free but he is always in chains." Rousseau believed in the natural goodness of humans and argued that society corrupts individuals. He believed that humans are inherently free, but they become enslaved by social institutions, inequality, and the influence of others. Rousseau`s ideas were influential in the development of modern political and social thought.
Option 1 - Locke: John Locke was a philosopher who believed in natural rights and the social contract theory, but he did not specifically make the statement mentioned in the question.
Option 3 - Bentham: Jeremy Bentham was a utilitarian philosopher who focused on the maximization of happiness, but he did not make the statement.
Option 4 - Robert Mill: There is no philosopher named Robert Mill, so this option is incorrect.