Fill in the blank with the suitable determiner by choosing the appropriate option from below :

When did you last see your parents ? _______ days ago.

A few

The correct answer is: A few.

A few is used to quantify countable nouns. In the sentence "When did you last see your parents? _______ days ago?", the noun "days" is countable.

A little is used to quantify uncountable nouns. For example, we say "I have a little bit of money."

Little and much are used to quantify nouns in general, without specifying whether they are countable or uncountable. However, they are not as specific as a few in this case.