Quick will mark brainliest

the graph shows the function f (x). which value is closest to the average rate of change from x=1 to x=3
a. -3.5
b. -2.3
c. -1.8
d. -0.3

Kayla wants to find the width, ab, of a river. she walks along the edge of the river 65 ft and marks point c. then she walks 25 ft further and marks point d. she turns 90° and walks until her location, point a, and point c are collinear. she marks point e at this location, as shown. (a) can kayla conclude that δ and δ are similar? why or why not? (b) suppose de = 15 ft. what can kayla conclude about the width of the river?