Classify this person's occupation as one of the following occupations: scientist, doctor, teacher, artist, engineer.
John Doe is a medical researcher who works in drug development.
John Doe is a scientist.
Complete the following task based on the instruction and optional input provided.### Instruction:
Classify this person's occupation as one of the following occupations: scientist, doctor, teacher, artist, engineer.

### Input:
John Doe is a medical researcher who works in drug development.

### Output:
John Doe is a scientist.