Choose something randomly based on its grouping

I have a game where the players are supposed to answer a question in 90 seconds using these rules:

1: It must contain words that are pulled from a group (easy words, medium words, etc.). This group might consist of 100+ words, but I need it to pull only 1, 2 or 3 words based on a variable that is set in the settings. (EX: the variable might be called "wordAmount")

2: It cannot duplicate the same word. (EX: if it pulls two words it CANNOT pull the same word for both)

3: I need the game to register if the answer has all of the required words, if not then it will not be entered into the pool to be randomly selected.

Also a little bonus question- would it be possible to have a variable randomly pulled and displayed on screen? (the variable will be a string that is set when the player writes their answer)

Thank you

-Vivian