Which of the following statements is TRUE if a moving object is slowing down?

1. A force that is causing the object to slow down must be increasing
2. A force within the object must be decreasing
3. A force is pulling it pushing forward must be decreasing
4. A force that is causing the object to slow down must be greater than the sum of the other forces that are pulling or pushing the object forward.

THIS IS SCIENCE ANSWER ASAP PLEASE!