His father is a doctor who treats children and infants.

Dermatologist
Gynaecologist
Podiatrist
Paediatrician

The correct answer is D. Paediatrician.

A paediatrician is a doctor who specializes in the care of children from birth to 18 years of age. They diagnose and treat illnesses and injuries, provide preventive care, and offer guidance to parents on child development and health.

A dermatologist is a doctor who specializes in the diagnosis and treatment of skin diseases.

A gynaecologist is a doctor who specializes in the diagnosis and treatment of diseases of the female reproductive system.

A podiatrist is a doctor who specializes in the diagnosis and treatment of foot disorders.