Concept:Use "some" in polite requests when referring to an uncountable noun.
Explanation:"Sugar" is an uncountable noun.
Option D, "a few", is incorrect because it is used only with countable nouns.
Option A, "much", is not natural in a polite request.
Option C, "a little", can be used with uncountable nouns, but it is less natural here.
In requests, "some" is normally used even in question form.
So the correct sentence is: "Can I borrow some sugar?"
Answer:B. some