At 2 and 4 I wouldn't expect them to do it on their own, but you can start teaching them
. i think giving that many options to a 2 year old would go right over their heads, but you might try giving two choices and helping the four yo think it through "how do you think we could solve this problem?"
my 4yo can think of solutions to problems, but we have been teaching it since she was tiny because she has an older sister to constantly work things out with