In the following displacement \((x)\) versus time \((t)\) graph, at which points \(P, Q\) and \(R\) will the object's speed be increasing?

1. \(R\) only
2. \(P\) only
3. \(Q\) and \(R\) only
4. \(P,Q,R\)

The accompanying graph of position \((x)\) versus time \((t)\) represents the motion of a particle. If \(p\) and \(q\) are both positive constants, the expression that best describes the acceleration of the particle is:
 

1. \(a=-p-qt\)

2. \(a=-p+qt\)

3. \(a=p+qt\)

4. \(a=p-qt\)