Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 18 to 22.

Renewable energy sources, such as solar and wind power, ___(1)___. Because of their renewable nature and minimal environmental impact, these energy sources are sustainable and environmentally friendly, offering a viable alternative to fossil fuels. ___(2)___.
Harnessing the potential of these technologies, ___(3)___. One of the primary benefits of renewable energy is its potential to reduce greenhouse gas emissions, ___(4)___. By utilizing the energy from the sun and wind, countries can decrease their reliance on coal, oil, and natural gas, which are major contributors to global warming. Additionally, renewable energy projects can create jobs and stimulate economic growth, thus making them an attractive option for policymakers.
However, there are challenges to widespread adoption, including the initial cost of setting up renewable energy systems and the need for technological advancements to improve efficiency. ___(5)___. Despite these obstacles, the future of renewable energy looks promising, with ongoing innovations and decreasing costs driving its growth.