Two young mathematicians think about limits.

Check out this dialogue between two calculus students (based on a true story):
Devyn
Riley, I want to play a game!
Riley
Ok. What’s the game?
Devyn
I’m thinking of a function. You are trying to figure out the output value of my function when the input is .
Riley
So if I call your function , I win if I can guess , right? What information do I have to work with?
Devyn
Right! You can ask for the output values for three different input values that are not . Any other input is ok.
Riley
I’m in! What’s ?
Devyn
When the input is , the output is , so . That’s one value down, two more. What do you want to know next?
Riley
What’s ?
Devyn
I think I see your strategy. .
Riley
With my last value, I’ll ask for .
Devyn
. Was that enough information for you to guess ?
What is ?
Which of the following best describes Riley’s strategy to find the value?
Which of the following properties would have given Riley a better chance at guessing the value?