learning problems

Script:

Kevin: Hi, Mom. Can you sign my report card?

Mom: Let me see... Your teacher said that there were promising signs of improvement in your academic performance. Great job, Kevin!

Kevin: Thanks, Mom. But the credit must go to this application I've been using on my tablet.

Mom: What application?

Kevin: It's a student assistant application with advanced AI technology that provides a new learning experience.

Mom: Is it that good?

Kevin: Yes. Like most artificial intelligence, this application will become smarter with more users' data.

Mom: How does it help you?

Kevin: Having feedback instantly after finishing an assignment is helpful for me. Using my results, the application also gives me more exercises in the area where I often make mistakes.

Mom: That's amazing.

Kevin: There is a new social network feature. My classmates are sharing their learning problems and I can share mine. This application is becoming popular in my school.

A. explore B. enormous C. become D. engine