Choose the word or phrase (a, b, c or d) that best fits the blank space in the following passage

Most of the energy we use today (1)_______ from coal, oil and gas. But these will not last for ever, and burning them is slowly harming the (2)_________. We need to (3)_______ other ways of supplying energy. Solar Power is a way of using the (4)_______ energy as heat or to make electricity. We can also use wind-power by building modern (5)_______ that spin in the wind. There are several types of water-power: river water in mountainous areas can (6)_______ to generate hydroelectric power, and we can also create electricity (7)_______ sea water flowing in and out with the (8)________.  

Most of the energy we use today (1)_______ from coal, oil and gas.