Correct option is D
Logic:
1) Rahul is older than Shashi but not as old as Kavita.
Kavita > Rahul > Shashi
2) Ashok is younger than Shashi but older than Monika.
Shashi > Ashok > Monika
3) Kavita is older than both Shashi and Ashok.
Kavita > Rahul > Shashi > Ashok > Monika
∴ Here, 'Monika' is youngest among all of them.
Hence, the correct answer is (d).