Solution:
The word 'indefinite' begins with vowel sound. Hence, article 'an' will be used.

Solution:
Use 'an' before words such as "hour" which sound like they start with a vowel even if the first letter is a consonant. Also use 'an' before letters and numbers which sound like they begin with a vowel, such as "F" or "8". Here MBA begins with 'em' and therefore 'an' article will be used.

Solution:
Here, 'owl' is a general bird and therefore indefinite article will be used. Word after the blank starts with vowel sound. 'An' article will be used.

Solution:
No article is required.

Solution:
'a' should be used before words with consonant sounds at the beginning and 'an' before words with vowel sounds at the beginning. The word 'Unique' has consonant sound 'yoo'. Hence, 'a' is used.

Solution:
Here, the sentence talks about the 'girl' as specific class. Since we are referring to specific things, we need to use the definite article 'the'.

Solution:
The noun here is nonspecific and singular, the 'question' could be any question, not a particular one. Hence we use indefinite article, particularly 'a', since the noun begins with a consonant.