Definition: In this task, you will be given a short story. One sentence from the story is chosen. Consider the events that happen before that sentence, or are likely to have happened before it. Does any of them directly cause it, or simply make it possible? You should write your answer in the form " A >causes/enables> B". Try to use phrases and sentences from the story to compose your answer when possible.
Input: story: Pam had a pen pal when she was 8. They wrote each other for 3 years. Pam suddenly stopped writing her pen pal. Ten years later, Pam ran into her pen pal. Pam and her pen pal are now best friends that hang out all the time.
 selected sentence: Pam suddenly stopped writing her pen pal.

Pam had a pen pal >Causes/Enables> Pam stopped writing her pen pal