阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。
A
Most Helpful Apps for Students
There's almost an app for everything nowadays, and this can make student life easier, cheaper, safer and more fun. Whether you want help with taking notes, revising, waking up on time or keeping fit， read on for our student app picks．
Lecture recording apps
Just a few years ago, students attending lectures would have to spend the entire time writing wildly on notepads, in order not to miss any vital bit of information. Then along came technology, and now， lecture recording apps are a reality.
Sound Note is a popular lecture recording app for iPad users. You can store an entire lecture in both visual and audio form. Other good quality lecture recording apps include Notes Plus and Audio Memos Free—The Voice Recorder.
Student planner apps
Organization is key for success and well-being at university, and student planner apps are becoming increasingly popular. As well as saving on paper, many student planner apps also send reminders and warnings straight to your phone or device. Popular student planner apps include Timetable, My Class Schedule and Class Timetable.
Student safety apps
A number of apps for students have been developed promoting personal safety if out alone at night. The Circle of Six app is particularly useful for locating lost friends on nights out and also allows users to send their circle of six friends an instant call for help at the touch of a button. The GPS tracker will mark your location on your friends’ devices, ensuring you'll always be able to find one another if necessary. Other student apps that promote safety include bSafe and React Mobile.
Healthy eating apps
If you're interested in eating healthily while keeping to a student budget, consider downloading a few healthy eating apps. Examples I've come across which are perfect apps for students include Rockin Ramen, a student app featuring a number of nutritious recipes with Ramen as a main ingredient, and MealBoard, an app which plans healthy meals, grocery shops and recipes based on what you've got in the fridge.
21. Which apps send reminders to users?
A. Student planner apps. B. Lecture recording apps.
C. Student safety apps. D. Healthy eating apps.
22. What can we learn about the Circle of Six app?
A. It allows users to seek help during an emergency.
B. It encourages users to communicate with friends.
C. It enables users to store an entire lecture.
D. It helps users to lead a healthy life.
23. The main purpose of the passage is to.
A. categorize apps B. introduce apps
C. evaluate apps D. compare apps
