The correct answer is 4. An electricity meter is commonly classified as an analog computer.

Option 1, mainframe computer, is incorrect. Mainframe computers are large, powerful machines typically used by organizations for processing large amounts of data. They are not typically used for measuring or monitoring electricity usage.

Option 2, microcomputer, is incorrect. Microcomputers, also known as personal computers, are smaller and less powerful than mainframe computers. While they can be used for a wide range of applications, including monitoring and controlling electricity consumption, they are not specifically designed or classified as electricity meters.

Option 3, hybrid computer, is incorrect. Hybrid computers combine the features of both analog and digital computers. They are typically used in specialized applications, such as scientific research or engineering simulations. Electricity meters do not fall into this category.

Analog computers, as mentioned in the correct answer, are devices that use continuous physical quantities, such as voltage or current, to represent and process information. Electricity meters measure the amount of electricity consumed and use analog computing principles to perform this task accurately.