Final answer:
According to Sternberg's triarchic theory of intelligence, the three aptitude categories are practical, creative, and analytical intelligence.
Step-by-step explanation:
Sternberg and colleagues (1999) conducted a study of 324 gifted high school students to determine their aptitude levels. According to Sternberg's triarchic theory of intelligence, there are three categories of aptitude: practical, creative, and analytical intelligence. Practical intelligence involves applying knowledge based on personal experiences to solve everyday problems, creative intelligence is about generating new and innovative ideas, and analytical intelligence focuses on academic problem-solving and critical thinking skills.