Each Question, Answer, Discussion post, Response, and Comment will generate a Notification to everyone in the class, unless an option such as "post directly to Instructors" or "post to selected groups" is chosen. 

Anyone who would like to stop receiving these notifications can do so in Preferences.

Select the user icon in the upper-right corner of the webpage. In the dropdown menu, select Preferences. Scroll down to Conversations. Select the Notifications tab and scroll down to Conversations. You can either turn off all Conversations notifications or select an individual course's Conversations notifications to mute.