What type of device senses and measures the acceleration of a body?

An accelerometer is the correct choice because it is specifically designed to measure the rate of change of velocity or acceleration of an object. It detects both the magnitude and direction of the object's movement, allowing it to provide data on changes in speed and orientation. This functionality is essential in various applications, including smartphones, automotive systems, and wearable devices, where understanding motion is crucial.

In contrast, a gyroscope measures angular velocity and orientation, but it does not directly measure linear acceleration. An altimeter measures altitude or height above a reference point, typically using atmospheric pressure or GPS data, which is not related to acceleration. A speedometer measures the speed of a vehicle, not the acceleration, focusing on how fast the object is moving rather than how its speed is changing over time.