Do you know Walk With A Doc? It is a new program . This program helps people to be healthy. It's not difficult to do it. You only need sports shoes and then go for a walk in a store or a park with two or more people at a time. David Sabgir is a doctor in the U.S.A. He starts the new health program. Every Saturday morning, Sabgir runs in a park and he starts thinking, "I run to help myself to be healthy. But I think I can help more people to be healthy." So he tells his friends and other people about this. They all like the idea. For the first walk, 101 people join. Later , more and more people join this health program. We only need _ if we want to join Walk With A Doc. A) a computer B) a basketball C) two buses D) sports shoes
D