Answer:
The answer is: a startling statistic.
Step-by-step explanation:
Startling can be defined as causing momentary surprise, astonishment or even fright. 
When you use a starling statistic or a startling statement, you will probably grab your audience´s complete attention right away. They are excellent starting points for a presentation. 
One of the best examples is Chris Anderson starting a presentation with: 
 “I'm going to tell you something that might surprise you: 
 Since the Stone Age, more than half of the deaths of 
 humankind have been from 1 disease.”