Which of the Following Observations Concerning Expert Systems Is True

Multiple Choice

Which of the following observations concerning expert systems is True?

A) These systems are not affected by any changes made to it.
B) These systems have lived up to the high expectations set by their name.
C) These systems are easy to develop and maintain.
D) These systems encode human knowledge in the form of If/Then rules.
E) These systems are typically used by experts.