Answer:
a. solar
Step-by-step explanation:
Solar energy is a renewable energy, obtained from the use of electromagnetic radiation from the Sun. The solar radiation that reaches the Earth has been exploited by humans since ancient times, through different technologies that have been evolving. Today, the heat and sunlight can be exploited by means of various sensors such as photoelectric cells, heliostats or solar collectors, which can be transformed into electrical or thermal energy. It is one of the so-called renewable energies or clean energies, which could help solve some of the most urgent problems facing humanity