Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Electricity is the most common form of energy used today.In the modern world, ___(1)___ is instantly available at the touch of a switch. Electricity has numerous uses. The most common use of electricity is to provide artificial lighting. In factories, electricity is used to ___(2)___ the electric motor of machines. In offices, electricity is used to light up ___(3)___ workplace. It is also used to operate air-conditioners, computers ___(4)___ many other machines.