21 A drone's descent from high above the school was recorded by students in the robotics class. The graph shows
the height of the drone after x seconds of descent.
y Drone Flight
60
55
50
45
40
Height of Drone (feet)
35
30
25
20
I
15
10
5
0
6 12 18 24 30 36 42 48
Time (sec)
A
B
What is the range of the function for this situation?
All real number less than or equal to 39.
All real numbers less than or equal to 55.
All real numbers greater than or equal to 0 and less than or equal to 39.
All real numbers greater than or equal to 0 and less than or equal to 55.
С
D
M