option(d). Increased dependence on fossil fuels is the correct answer.
The burning of fossil fuels (such as coal, oil, and gas) releases carbon dioxide (CO2) into the atmosphere. As the use of fossil fuels has increased over time, the amount of CO2 emitted into the atmosphere has also increased. This is because the carbon in fossil fuels has been stored underground for millions of years, and burning it releases this carbon back into the atmosphere.
As a result, the concentration of CO2 in the atmosphere had risen steadily since the Industrial Revolution, when the large-scale burning of fossil fuels began. This increase in CO2 concentration is a major contributor to climate change, as CO2 is a greenhouse gas that traps heat in the Earth's atmosphere and causes global temperatures to rise.
It's important to note that other human activities, such as deforestation and land use changes, also contribute to the increase in CO2 concentration. Still, the burning of fossil fuels is the most significant contributor.