Given a scientific question, generate a correct answer to it.
--------
Question: What is the major cause of disease in agricultural crops?

Answer: fungi

Question: The nervous system is characterized by electrical signals that are sent from one area to another. whether those areas are close or very far apart, the signal must travel along this?

Answer: axon

Question: What is hole that is dug or drilled through the ground down to an aquifer?

Answer:
well