题目选项分析

Although alternative energy sources, such as solar energy and wind farms, both of which easily could supply all of the US's energy needs, are more expensive to set up than fossil fuel power, they would provide vast savings over time, not only in direct upkeep, but also in medical costs due to lower cancer rates.

Exemplified by solar energy and wind farms, both of which easily could supply all of the US's energy needs, alternative energy sources are more expensive to set up than fossil fuel power, they would provide vast savings over time, not only in direct upkeep, but also in medical costs due to lower cancer rates.