Hree friends are talking about what they think causes shiny pennies to turn dull. Deandre says, "I think they turn dull because they're exposed to the air over time." Jamie says, "I think they turn dull because they get dirt on them from being dropped on the ground." Selina says, "I think there is dull metal inside the penny the entire time." Who do you agree with most and why?

Deandre is correct.

Explanation:

When shiny pennies turn dull, due to getting rust. It gets cover with a layer of black or brown color on its surface on the exposure of air.

In this problem,

Deandre says, "I think they turn dull because they're exposed to the air over time." Jamie says, "I think they turn dull because they get dirt on them from being dropped on the ground." Selina says, "I think there is dull metal inside the penny the entire time.

Out of three friends, Deandre is correct. Shiny pennies turn dull because they're exposed to the air over time.