Read this sentence from paragraph 1 of "YouTube: A World of Knowledge and Fun at Your Fingertips."

If the original YouTube founders had had a crystal ball, they might not have been so quick to sign on the dotted line!

The phrase "had a crystal ball" refers to the YouTube founders ​
____ 1. believing in fortune-tellers 2. owning something expensive 3. being dedicated and hardworking 4. knowing what happens in the future

4. knowing what happens in the future