Let us assume that the price of the 3 books are x, y and 1.5 (all figures in $)

Now, the mean is (x+y+1.5)/3=1.5

so, x+y=3, lets assume x>1.5, then y<1.5
if y>1.5 then x<1.5

If x=y, then both have values of 1.5

Whatever the values of x or y, when arranged in ascending order the price of the 3rd book (1.5) will be the middle value hence the median is also 1.5

so, both values are equal hence option C