Aspeed-time graph shows that a car moves at 10 m/s for 10 s. the car’s speed then steadily decreases until it comes to a stop at 30 s. which of the following describes the slope of the speed-time graph from 10 s to 30 s?
a. linear, horizontal
b. curved, upward
c. linear, sloping downward
d. linear, sloping upward

At any point on the graph, the height of the line above the x-axis
shows the car's speed at that time.

Since the car is slowing down in the time between 10s and 30s,
the graph must be dropping lower and lower during that time.

Also, since you said that the car's speed decreases steadily,
the slope of the graph is constant, and the graph is a straight
line. 

So, during that time, the graph is a straight line, sloping downward.
(Choice 'C'.)

When you go to ask a qustion there will be a picture of a paper clip looking thing and then it will pop up your files and you click on the imajes and then you up load it

When seismic waves hit a fault, the waves are reflected off the fault. seismograph can detect these reflected seismic waves. geologists then use these data to map the fault's length and depth