The correct answer is C) nuclear power.
The energy source that has been most affected by safety concerns is "nuclear power."
There have been numerous accidents in nuclear power plans that raised many safety concerns about nuclear power. Let's remember the horrible accidents in Chernobyl, Russia or in Japan. Many people die and the consequences of the explosion provoked so much radiation and polluted the air and the water of those regions. Environmentalists consider that nuclear power has not to be considered in the future of humanity as a source of energy. It is not a safe or clean source of energy.