Choice A is the answer you're seeking. Edmund Burke warned that the colonists faced threats to their liberty because they were so familiar with slavery.
Now, just because Burke was talking about liberties in that speech, don't think of him as someone always rallying for liberties and more liberties. Burke is famous as one of the leaders of the Conservative movement of the late 18th and early 19th century. When the French Revolution began (after the American Revolution), Burke wrote a hugely famous and influential book, "Reflections on the Revolution in France" (published in 1790). In that writing, Burke warned against the excesses of freedom that he predicted would occur in France because of its Revolution -- and many of his predictions came true.
Burke wanted liberties and freedoms to grow naturally, organically -- rather than by revolutionary upheavals.