Answer:
a. t
b. a (or x = a)
c. r
d.
1) c
2) t
3) a
4) p
Explanation:
a. Draw vertical line passing through the point (c,0). This line intersects the graph at point L. Point L has coordinates (c,t), so

b. If
draw the horizontal line passing through the point (0,p). This line intersects the graph at point K with coordinates (a,p), so

c. Note that
then

d. Coordinates of point L are (c,t), coordinates of point K are (a,p)