Sharon's teacher, Mr. Armus, has developed a special software program for her and other students to use in his calculus class. Students can select specific topics to focus on for more practice and, after attempting to solve several problems related to the topic, correct answers are given, along with explanations of why other answers are incorrect. The program also suggests, based on student
responses, additional problems to try and solve. Mr. Armus has developed and is using:

a. an intelligent tutoring system.
b. project-based learning.
c. process-based learning.
d. knowledge transforming system.