Select the most appropriate idiom that can substitute the italicised words in the given sentence.

He was sacked from his job because of a grave error on his part.

Himalayan blunder

The most appropriate idiom that can substitute the italicised words in the given sentence is Himalayan blunder.

The idiom "Himalayan blunder" is used to describe a very serious mistake. It is often used to describe a mistake that has caused a lot of damage or embarrassment.

In the given sentence, the speaker is saying that the man's mistake was so serious that it cost him his job. Therefore, the idiom "Himalayan blunder" is the most appropriate choice.

Here are some other examples of how the idiom "Himalayan blunder" can be used in a sentence:

• "The company made a Himalayan blunder when it launched a product that was full of bugs."
• "The politician made a Himalayan blunder when he made a racist remark on live television."
• "The general made a Himalayan blunder when he led his troops into a trap."