D. Lower Epidermis - Bottom layer of leaf, containing stoma and guard cells, which open and close to allow gas and water exchange.
(leaf; containing; stoma and guard cells, which open and close to allow gas and water exchange) (stoma and guard cells; to allow; gas and water exchange)
leaf stoma and guard cells
containing to allow
stoma and guard cells, which open and close to allow gas and water exchange
gas and water exchange