Final answer:
A positive slope on a velocity versus time graph indicates positive acceleration, and a positive, upward-curved line on a position versus time graph indicates the object is moving forward with increasing velocity. So the correct answer is d. positive, a line curved upward.
Step-by-step explanation:
The slope of the velocity versus time graph of an object with positive velocity and acceleration is positive, and the shape of the position versus time graph is a line curved upward. Therefore, the correct answer to the question is d. positive, a line curved upward. When an object's velocity increases over time due to positive acceleration, it means that the graph of velocity versus time will show a rising line. This slope represents the rate of change of velocity with respect to time, which is acceleration. Since we are given that both the velocity and acceleration are positive, the slope must be positive. Similarly, a position versus time graph for an object with positive velocity that is increasing (positive acceleration) will be a curve, and because the position is continually increasing over time, this curve will be upward, concave upwards.