Which of the Following Is a Benefit of Instant Messaging

Which of the following is a benefit of instant messaging?

A) Instant messaging allows real-time communication with colleagues anywhere in the world without Wi-Fi or a cell phone signal.
B) Instant messaging is more effective than using a telephone.
C) Instant messaging ensures people are more productive on the job.
D) Instant messaging and texting are low-cost substitutes for voice calls.