SOLUTION:

This is a problem on Percentage and Probability

Let there be "x" flowers

Number of roses = 40% = 0.4x

Number of carnations = 100-40=60% = 0.6x

1/4 of the roses = 1/4 * (0.4x) = 0.1x and

1/10 of carnations = 1/10 * (0.6x) = 0.06x are RED

Probability that a red flower selected at random is a rose= 0.1x / 0.16x

 = 5/8 (OPTION B)