Q: Fact 1: Using a gasoline engine requires burning gasoline. Fact 2: Fossil fuels include coal, oil, natural gas, and gasoline. Given the two facts above, what does an engine require burning?

OPT:
(1). Time and energy;
(2). energy;
(3). wind;
(4). water;
(5). carbon dioxide;
(6). layers of fat;
(7). fossil fuels;
(8). sunlight;
A:
(7).