The correct answer is in parallel (option C). Household electrical appliances like fans and bulbs are generally installed in parallel. In a parallel circuit, each appliance has its own separate connection to the power supply. This configuration allows each appliance to operate independently of the others. If one appliance is turned off or malfunctions, the others remain unaffected and continue to function normally. This setup is convenient for household applications because it provides flexibility in operation and maintenance. It also ensures that the failure of one appliance does not affect the operation of others, enhancing reliability and convenience. Parallel installation is common in homes to accommodate the diverse usage patterns and preferences of occupants, allowing different appliances to be controlled and used independently as needed.