The piece of evidence that best supports the claim that "every person should adopt a pet as soon as can" is: "A new American Heart Association survey of a thousand pet owners found that 95% rely on their animal companions for stress relief."
This evidence provides statistical support that a significant majority of pet owners find value in their pets for stress relief, which directly correlates to the benefits of adopting a pet. It emphasizes the positive impact pets have on people's lives, reinforcing the argument for adoption.