The correct answer is 1, 2, and 3. Acceleration refers to any change in an object's velocity, which includes both speeding up (statement 1) and slowing down (statement 2). Additionally, when an object changes direction (statement 3), it is also considered to be accelerating because its velocity is changing. However, an object that is at rest (statement 4) does not have any change in velocity, so it is not an example of acceleration. To understand which statements describe acceleration, you need to know the definition of acceleration and apply it to each statement.
