Zara has a collection of 4 marbles: an Aggie, a Bumblebee, a Steelie

Zara has a collection of 4 marbles: an Aggie, a Bumblebee, a Steelie

Zara has a collection of 4 marbles: an Aggie, a Bumblebee, a Steelie, and a Tiger. She wants to display them in a row on a shelf, but does not want to put the Steelie and the Tiger next to one another. In how many ways can she do this?

(A) 6 (B) 8 (C) 12 (D) 18 (E) 24

answer：C