Orifice plates, venturi tubes and nozzles belong to the group called:

Orifice plates, venturi tubes, and nozzles are devices used to measure the flow rate of fluids in a system by creating a differential pressure as the fluid passes through them. These devices operate based on principles of fluid dynamics, specifically Bernoulli's equation, which relates the speed of fluid flow to its pressure.

The term "flow meters" is a broad category that encompasses various devices designed to measure the flow of liquids and gases. Orifice plates, venturi tubes, and nozzles are specific types of flow measurement devices because they determine the flow rate by measuring changes in pressure created as fluids flow through different cross-sectional areas. By calculating the pressure difference, one can derive the flow rate of the fluid passing through the system.

In contrast, the terms given for the other options do not describe the primary function of measuring flow: analog meters typically represent devices that measure physical quantities in a continuous manner; pressure meters focus specifically on measuring pressure rather than flow; and head meters measure the height of fluid, which can be related to pressure but does not directly measure the flow rate like flow meters do.

Therefore, "flow meters" identifies the specific category to which orifice plates, venturi tubes, and nozzles belong based on their