On a Position-Time Graph for a Particle,suppose the Plot Starts

Multiple Choice

On a position-time graph for a particle,suppose the plot starts at some positive position and as the time goes on the curve gets steeper and steeper while curving upwards.Which of the following must be true?

A) The speed of the particle is constant.
B) The acceleration of the particle is constant.
C) The speed of the particle is decreasing.
D) The acceleration of the particle is positive.