Choose the correct meaning of the underlined idiom in the sentence:

The Swedish scientists realized that they had been barking up the wrong tree.

Following the wrong course of action.

The correct answer is Option (2) - Following the wrong course of action.

Explanation:

• The phrase originates from hunting, where a dog might bark at the base of a tree believing the prey is there when it is not.
• It metaphorically means pursuing a mistaken or misguided approach.
• It implies that someone is pursuing a line of inquiry or action that is unlikely to yield the desired results.