Question

in the 1970s, what element was removed as an additive from gasoline? zinc copper lead palladium

Explanation:

In the 1970s, lead was removed from gasoline as an additive (specifically tetraethyl lead, used to prevent engine knocking) due to environmental and health concerns related to lead pollution. Zinc, copper, and palladium were not common gasoline additives removed in the 1970s.

Answer:

lead (the option corresponding to "lead" among the choices)