Which of the following is the best example of an opening sentence for a speech?

A) I want to inform you of the warning signs of cancer.
B) Today we will talk about the warning signs of cancer,so everyone can know what to look for.
C) Three years ago,one of my best friends--a young woman about your age--was told she had cancer.
D) ​Most of you are unaware of the warning signs of cancer,but you should be;so I am going to tell you about them.