The correct answer is: D. algorithms
Algorithms are a set of instructions that are followed to solve a problem. They are the foundation of artificial intelligence, and they are used in a wide variety of applications, from search engines to self-driving cars.
Smell, touch, and symbols are all important aspects of human intelligence, but they are not typically considered to be part of artificial intelligence. However, there is some research being done on developing AI systems that can smell and touch, and it is possible that these capabilities will become more common in the future.
None of the above is not the correct answer, because algorithms are a key component of artificial intelligence.