The negative aspect of fossil fuels is that they cause pollution on Earth.
The correct answer is that fossil fuels cause pollution on Earth. Fossil fuels, such as coal, oil, and natural gas, when burned to produce energy, release greenhouse gases and other harmful pollutants into the atmosphere. These pollutants contribute to air pollution, which can have serious negative impacts on human health and the environment. To determine this, one can analyze the different aspects of fossil fuels and evaluate their potential negative effects. In this case, one can consider the pollution caused by the burning of fossil fuels as the negative aspect.
