The correct answer is option 2), i.e. Alas! John could not get through the examination. Explanation:
Option 1) is incorrect. The question mark is used after asking a question. Example: What is her name?
Option 2) is the correctly punctuated sentence.
Option 3) is incorrect. A comma is used when someone is directly addressed OR to separate two clauses/to separate ideas, objects, names in a sentence. Example: I will go to Goa, Mumbai and Pune.
Option 4) is incorrect. The full stop is used at the end of a sentence. Example: She is my sister.