I think B (Every fifth student from each grade)
A only talks about female students, C talks about students on a sports team which would be biased since the students on the sports team probably get more exercise, and d would be ok but not the best since some last names are more common and others you would get only a very small sample size.
Answer:
4.09 m
Step-by-step explanation:
Let the length of the shadow cast by a person be x m.

Refrection across the y-axis changes the function to y = |-x|.
Vertical stretch by a factor of 1.5 changes the graph to y = 1.5|-x|
Shifting the graph by 4 units downward changes the graph to y = 1.5|-x| - 4
Required equation is y = 1.5|-x| - 4
Answer
Step-by-step explanation:
Law of sines: SinB/15 = SinA/BC
B = 90
A = 180-90-21=69°
BC= (15*SinA)/SinB = (15*sin69)/1 ≈ 14m