Select the most appropriate option to fill in the blank.--------- mon…

The correct answer is Option (2) → The little

Little, a little and the little:

• Little means hardly any (a negative sense): There is little hope.
• A little means some, a small amount (a positive sense): Add a little sugar.
• The little means the small amount that there is, all of it; it points to a particular quantity.
• Clue: "that you are earning", which points to a particular amount.
• This sentence: "that you are earning" points to a particular amount, the small income you have, and all of it should be saved from waste, so The little is needed.
• Complete sentence: The little money that you are earning should not be wasted.
  Example: She spent the little money she had on books.

Why the Other Options are Incorrect?

Option 1: A little — Incorrect. A little means some, an unspecified small amount; it does not point to the particular amount named by "that you are earning".
Example: Please add a little salt to the soup.

Option 3: Any — Incorrect. Any means no matter which or how much; it does not express the idea of a small amount, which is what the sentence is about.
Example: You can take any book from the shelf.

Option 4: Very little — Incorrect. Very little means almost none; "very little money ... should not be wasted" would mean that hardly any money should be saved from waste, the opposite of the advice.
Example: There is very little water left in the tank.

Contrast: a little means some unspecified small amount; the little means all of the particular small amount there is.