Final answer:
The criteria for someone to be categorized as having a developmental disability is having a below-average IQ and exhibiting significant limitations in two or more adaptive skills.
Step-by-step explanation:
The key criteria for someone to be categorized as having a "developmental disability" are:
- Having a below-average IQ
- Exhibiting significant limitations in two or more adaptive skills
Therefore, the correct answer to the question is Option c) Both a and b.