Which item is a computer output device?

A computer output device refers to components that receive signals from the vehicle's engine control module (ECM) or other onboard computers to perform specific actions based on data collected from various sensors.

In this scenario, all the items listed are functional components that can be considered output devices as they act upon commands issued by the vehicle's computer system.

The fuel injector is responsible for delivering the correct amount of fuel into the engine based on the information the ECM receives, such as engine temperature and load conditions. The transmission shift solenoid is used to control the flow of transmission fluid, enabling the transmission to shift gears effectively as directed by the computer based on vehicle speed and engine load. The evaporative emission control solenoid helps in managing fuel vapors from the fuel system, contributing to the vehicle's emission control system, again receiving directives from the ECM.

Thus, since all of these components operate as output devices receiving and acting upon electronic signals from the vehicle’s computer, it is correct to say that they collectively function as computer output devices.