Correct Answer - Option 3 : Vikas
From the statements:
Manish is older than Rohan and Vikas is younger than Naveen and Rohan.
Manish > Rohan, Naveen / Rohan > Vikas
Manish is older than Naveen.
Manish > Naveen
On combining both the statements, we get:
Manish > Naveen / Rohan > Vikas
Thus, we can see that Vikas is the youngest.
Hence, Vikas is correct.