Option C is correct as 'The' refers to a particular subject & shows uniqueness of subjects of which readers are aware of. The Birmingham Museum is unique. No article required before last year.

Here, sentence talks about 'time' as general class of things. Since we are referring to general things, we need to use definite article 'a'.

For general things indefinite article is used. The sound of word 'European' starts with 'yoo' refore 'a' article is correct.

Here, 'Cat' is a general class and refore indefinite article will be used. Word after blank starts with consonant sound. 'A' article will be used.

'this school' indicates a particular school and hence article '' will be used before teachers.

Use 'an' before words such as "hour" which sound like y start with a vowel even if first letter is a consonant. Also use 'an' before letters and numbers which sound like y begin with a vowel, such as "F" or "8". 'An' will be used before 'S.D.O.'.

No article is required.

As it is mentioned 'Principal' we know that a specific school is being talked about. Hence, definite article '' will be used.

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

Here, 'Guitar' is a common noun and we can easily figure out that speaker's far will buy her/him single guitar. Hence, indefinite article 'a' will be used as word starts with a consonant sound.