ANSWER:
The correct answer is a. some.
STEP-BY-STEP EXPLANATION:
Because writers must choose which life events to include, some biographies are biased or unbalanced in some way regardless of who the writer is.
Countable and uncountable
Some is used with both countable and uncountable nouns:
Countable Nouns - 'Some people in my school like Jazz.'
Uncountable Nouns - 'There was some snow here last winter.'
Positive sentences
Some is used in positive sentences
'I have some friends.'
'We bought some coffee.'
Offering
We use some in questions when we expect the answer to be 'yes' or when we are offering something, otherwise, we use any:
'Would you like some milk?
Requests
Some is also used in questions when we are making a request:
'Can I borrow some money?'
