The listening part has argued against the points that are discussed about the the ways agnostids lived.

First, the reading state that the agnostids are known as the primitive arthropods that cause the agnostids a predator to hunt small organisms. However, the professor argues against this theory because other primitive arthropods have well developed eyes and vision to track their prey. But the agnostids do not have a good vision, even some of them are completely blind. Also, they do not have sensitive organs that help them to prey. Therefore, we can conclude that the agnostids are not predators. 

Second, it shows the agnostids inhabit on the seafloor as other primitive arthropods and they sead dead organisms and bacteria as the source of food. Hence, the professor proves that the organisms live on seafloor move slow and they dwelled in the constant area.

Third, the reading suggest that the agnostids might be parasites because there are many example species are shown in nowadays that are day arthropods. But, the listening part says the population of the parasites are not very large because parasites need to stay in limit in order to make sure they won't kill their host.