Articles are very important words in English and so is their knowledge.
There are two kinds of articles.
(i) Indefinite Articles —A, An (in the sense of 'one' and 'any)
(ii) Definite Articles—The (in the sense of 'this' and 'that')
Rules of Articles
The Use of Indefinite Articles 'A', 'An'
A student must note that the choice between 'A' and 'An' is determined primarily by SOUND.
(A) 'A is used before a word beginning.
(i) With consonant, e.g.,
a boy a child
a student a book
(ii) With a vowel giving the sound of a consonant, e.g.,
a one eyed man a university student
a European a unique book
a uniform a universal problem
(B) 'An' is used before a word beginning.
(i) With a vowel, e.g.,
an elephant an apple
an ass an umbrella
(ii) With a mute 'h'. e.g.,
an hour an heir
an honourable person an honest man
an honorary post an hourly visit
(iii) With a consonant pronounced with the sound of a vowel, e.g.,
an LL.B student an MR
an M.L.A. an S.P.
an X-ray an F.I.R.
See more examples;
A. a B. an C. the D. none
A. a B. an
C. the D. Could be both "a" and "the"
A. a B. an C. the D. None
A. an B. a C. the D. no article needed
A. a B. an C. the D. no article needed
1. B; 2. B; 3. A; 4. B; 5. A