A brief study distributed to college students to investigate the usage of communication tools like (email, threaded discussion and real-time chat) based of the following statistical analysis for Mean...

A brief study distributed to college students to investigate the usage of communication tools like (email, threaded discussion and real-time chat) based of the following statistical analysis for Mean and standard deviation, which one of the tools has the most variable data?
using email (M = 4.13, SD = 0.43), threaded discussion (M = 3.55, SD = 0.85), and real-time chat (M = 3.02,SD = 1.04)