求助一道数学题

A gardener is going to plant 2 red rosebushes and 2 white rosebushes. If the gardener is
to select each of the bushes at random, one at a time, and plant them in a row, what is the
probability that the 2 rosebushes in the middle of the row will be the red rosebushes?
A. 1/12
B. 1/6
C. 1/5
D. 1/3
E. 1/2

答案是B.  本人的思路: P2.2/ P3,1 不知是否正确,请NN确认.

5辆车排成1排,1辆黄车,1辆兰车,3辆红色车,且3辆红车不可分辨,问有多少种排法?

P5,2  不知此思路可否正确?

第一个是 1/2 * 2/3 * 1/2=1/6

多谢楼上的兄弟，ＧＯＯＤ　ＬＵＣＫ!