The correct option is B a/no article
OPTION "B" is the correct answer.
EXPLANATION:
There are two types of articles:
DEFINITE ARTICLE (THE) : Article 'the' is used to refer to a DEFINITE thing or person.
INDEFINITE ARTICLE(A/AN): Article 'a/an' is used to refer to a thing or person in general. For instance: man, door etc.
Article 'a' is used with consonant sounds whereas article 'an' is used with vowel sounds.
In the FIRST Blank, article "a" will be used as the sentence is referring to something general.
In the SECOND blank, "no article" will be used because "no article" is used when the speaker is mentioning someone"s appearance ( with dark hair) for the second time. And again, 'hair' is uncountable noun.