Definition: In this task, you are given two statements. The task is to output whether a given textual premise, i.e. Statement 2, entails or implies a given scientific fact, i.e. Statement 1. The output should be 'entails' if Statement 2 supports Statement 1 and should be 'neutral' otherwise.
Input: Sentence 1: Heart valves prevent the backflow of blood from happening in the heart. Sentence 2: These valves open and close depending on the phase of the heart beat to allow the blood to flow from one chamber of the heart  to another and to prevent the backflow of blood.

entails