Which net diagram represents this solid figure?

 The answer is the second optional figure. Image is attached herewith.

Step-by-step explanation:  We are given a picture of a solid with dimensions 2 units, 3 units and 5 units as shown in the figure. We are to select the correct net diagram for the solid from the four optional figures.

We can easily that if we open up the solid from all sides, it will look exactly same as the second optional figure. One may also try to do so with a piece of paper.

The solid and its net diagram is shown in the attached figure.

Thus, second option is correct.

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."