In the following question, an idiomatic expression or proverb is highlighted. Select the alternative that best describes its use in the sentence.
We are throwing a party for our friend Jockey, but it's a surprise, so don’t tell him anything about it. Mum’s the word.
1
Make a promise
2
Keep quiet and say nothing
3
Say as much as required
4
Stay angry
5
Stop badmouthing people