Final answer:
The background color of a presentation does not always need to remain constant, but should maintain a consistent visual style and consider accessibility for all audience members.
Step-by-step explanation:
The background color of a presentation should not necessarily remain constant. While it's often important to keep a consistent visual style throughout a presentation, including font, colors, backgrounds, and so on, there might be strategic reasons to change the background for different sections or topics for emphasis or organization.
Especially when considering accessibility, it's important to ensure that your presentation is easily understandable for all audience members, including those with visual impairments or who rely on interpreters. To assist with this, the background should offer sufficient contrast with text and other elements to ensure readability. Presentations should also provide space and time for the audience to interpret and process the information presented, bringing clarity rather than confusion.