The one that has the largest impact on opportunity cost is: Limited resource
Opportunity cost refers to the situation when we have to sacrifice a certain type of option in order to pursue another option and limited resource tend to have the largest impact on this situation.
For example Let's say that you wanted to buy both a phone that cost $300 and a laptop that cost $400, but you only have $ 500 in your pocket (you have limited resource). In such situation, you would have to sacrifice one of the products as opportunity cost and obtain one product that can you afford.