If Kelly buys t pens priced at 2 dollars each and u pens priced at 4 dollars each, which of the following expresses, in terms of t and u, the average (arithmetic mean) price, in dollars, of these pens?
(A) (3 times t) + (3 times u) over (t + u)
(B) (3 times t) + (3 times u) over (t imes u)
(C) (3 times t times u) over (t + u)
(D) ((2 times t) + (4 times u)) over (t + u)
(E) ((2 times t) + (4 times u)) over (t times u)
