**Concept:** The question tests on the basics of Counting

**Solution**

4 consonants can be chosen out of 7 in 7C4 = 7C3 = (7 * 6 * 5) / (3 * 2 * 1) = 35 ways

2 vowels can be chosen out of 4 in 4C2 = (4 * 3) / ( 2 * 1) = 6 ways

These chosen letters can be arranged in 6! = 720 ways

Total number of ways = 35 * 6 * 720 = 151200 ways

Option C