Pick out the correct sentence: (A) A girl who came here yesterday is…

The correct answer is Option (3) → (B) Only

Definite article with a defining clause:

• A clause such as "who came here yesterday" points out one particular person.
• A noun made particular in this way takes the.
• A singular countable noun such as "girl" cannot stand without an article.
  Example: The boy who sits next to me is my cousin.

(A) A girl who came here yesterday is my friend. — Incorrect.

• The girl is a particular person pointed out by the clause, so "a" does not fit.
• Correct form: The girl who came here yesterday is my friend.

(B) The girl who came here yesterday is my friend. — Correct.

• The goes with the particular girl, and the relative pronoun who joins the clause.

(C) Girl who came here yesterday is my friend. — Incorrect.

• The singular countable noun "girl" has no article.
• Correct form: The girl who came here yesterday is my friend.

(D) The girl came here yesterday is a friend. — Incorrect.

• The relative pronoun who is missing, so the sentence has two verbs ("came", "is") with nothing to join them.
• Correct form: The girl who came here yesterday is a friend.

Tip: In this question the options do not follow the order of the statements (Option 1 = (D) Only, Option 2 = (C) Only, Option 3 = (B) Only, Option 4 = (A) Only). NTA often jumbles the options in this way, so after finding the correct statement, read the options carefully and mark the one with the right letter.