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'.)

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answer and explanation;

composition refers to both the types of minerals within a rock and the overall chemical makeup of the rock while texture refers to the size and arrangement of the minerals or grains that make up a rock. both composition and texture can be used to classify rocks, such as igneous rocks. texture describes how the rock became solid or crystallized from liquid, melted rock. composition of a rock describes the minerals that make up a particular rock.