16. There are two Arabic books, three German books, and four Spanish books, a total of nine books on a bookshelf. If the two Arabic books are to be placed together and the four Spanish books are to be placed together, then there are ( ) ways.
(A) 1440
(B) 2880
(C) 5760
(D) 182440
(E) 362880
16. C.

Since the two Arabic books and the four Spanish books must be placed together respectively, we can consider them as a single unit each. This means we only need to consider the arrangement of one Arabic book, one Spanish book, and three German books, which gives us $5!$ ways.

Additionally, the two Arabic books can be arranged in 2! ways, and the four Spanish books can be arranged in 4! ways, so the total number of arrangements is
$$
2! \times 4! \times 5! = 5760
$$