"to take the plunge" A) to commit to a decision (often one that makes you nervous) / B) to fall down (from a very high place) / C) to make a choice (especially between two similar options)

"to pull someone's leg" A) to make someone uncomfortable or anxious / B) to fool or joke someone / C) to make someone happy about something

"To be a piece of cake" means:

"once in a blue moon" A) usually / B) never / C) rarely

"to be left out in the cold" A) to be alone / B) to be excluded / C) to be freezing

"To kill two birds with one stone" means:

"to bite the bullet" A) to do something that makes you nervous / B) to do something that makes someone else uncomfortable / C) to make yourself do something difficult or unpleasant

"To hit the nail on the head" means:

"To kick the bucket" means:

"To have a chip on your shoulder" means:

"to be under the weather" A) to be strong / B) to be sad / C) to be ill

"To be on the same page" means:

"To have a skeleton in the closet" means: