Permanent and semi permanent machines always powered by . . . . . . . .

The correct answer to this question is D, Electric.

Permanent and semi-permanent machines, such as electric shovels, drills, and haul trucks, are always powered by electricity. They are typically connected to the power supply system of the mine or a nearby substation through cables and conductors.

Electric power is preferred over other types of power sources, such as diesel or kerosene, for several reasons. Electric power is cleaner, more efficient, and more economical than other types of power. Electric machines also produce less noise and air pollution, making them more environmentally friendly.

Electric power can be generated from various sources, including coal, natural gas, nuclear, hydro, and renewable energy sources such as solar and wind power. The choice of power generation depends on several factors, including availability, cost, and environmental impact.

Therefore, the correct answer is D, Electric.