Question: Ada was playing kickball. She kicked a ball into the gravel and noticed it was warm when she picked it up. She kicked it again onto a grassy hill, but this time the ball wasn't very hot when she retrieved it. In which surface did the ball travel the most? (A) gravel (B) grassy hill  Do not use A and B to answer the question but instead, choose between "gravel" and  "grassy hill".
A:
grassy hill