She aleays spends a lot of money ( ) clothes.

B,spend money on sth.花钱在某物上面。

b spend money on sth.花钱在某物上面。固定词组 但还有个是spend time in doing sth花时间做某事

in 后面跟时间

on后面跟物或事

所以选B

on
spend money on sth.

spend some time/money on sth
spend some time/money in doing sth

buying