Answer:
The correct option is:
 Periodic with period 3 and amplitude of about 7.5
Explanation:
We are given a data set as:
Hour Number of bikes
 1 5
 2 19
 3 14
 4 4
 5 19
 6 15
 7 6
 8 22
 9 15
 10 5 
 11 20
 12 16
From this data set we could clearly observe that the values are periodic as it repeats after every 3rd value.
{(1,5), (2,19) , (3,14)} {(4,4),(5,19),(6,15)} {(7,6),(8,22),(9,15)} {(10,5),(11,20),(12,16)}
Also, the amplitude is the distance is calculated as:

( Since, amplitude is the distance of the maximum or minimum value from the mid-line)
for first set:

for second set:

for third set:

for fourth set:

Hence, approximately the amplitude is:
7.5