What Option do I want? Why not both?

I am looking at 2018 Volts on the Chevrolet website. I like to research a little before talking to the dealer because now and then they are misinformed and don't get me the straight answer I need.

When I build and price under saftey 2, it lists 2 options. See descriptions below. It only allows me to select one. If I try to select the other one too, the first is un-selected.

I would like to have both of these features. What do I not understand here.

Thanks for any advice from those who have a Gen 2 or understand the options.


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Low Speed Forward Automatic Braking

If the vehicle is traveling at a low speed and the system detects that a front-end collision situation is imminent while following a detected vehicle and the driver has not already applied the brakes, the system automatically applies brakes to help reduce the collision’s severity1
The system may even help avoid the collision at very low speeds
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or

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Forward Automatic Braking

If the system detects that a front-end collision situation is imminent while following a detected vehicle, and the driver has not already applied the brakes, the system automatically applies brakes to help reduce the collision’s severity1
The system may even help avoid the collision at very low speeds
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