The phrase “a few” is used with countable nouns to indicate a small number.
Since “notes” is a countable noun, “a few” is the correct choice to indicate a small quantity.
The sentence reads: “There are only a few notes in his wallet.”
Thus, the correct answer is (A) a few.
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?