One Word Substitution

A doctor who treats children is called a Pediatrician. The other options have different meanings: Pedophile refers to an adult attracted to children, Fatalist believes in fate, and Pedagogue means a teacher.

A 'fresco' is a technique of mural painting executed upon freshly laid lime plaster, commonly used for wall paintings, including watercolor-like pictures on walls. The other options do not relate to wall paintings.