I would say that the answer is A.
Answer:

Explanation:
P = Acoustic power = 63 µW
r = Distance to the sound source = 210 m
Acoustic power

Threshold intensity = 
Ratio

Ratio of the acoustic intensity produced by the juvenile howler to the reference intensity is 113.68
Answer:
C) The function F(x) for 0 < x < 5, the block's initial velocity, and the value of Fr.
Explanation:
Yo want to prove the following equation:

That is, the net force exerted on an object is equal to the change in the kinetic energy of the object.
The previous equation is also equal to:
(1)
m: mass of the block
vf: final velocity
v_o: initial velocity
Ff: friction force
F(x): Force
x: distance
You know the values of vf, m and x.
In order to prove the equation (1) it is necessary that you have C The function F(x) for 0 < x < 5, the block's initial velocity, and the value of F. Thus you can calculate experimentally both sides of the equation.
Answer:
Por lo tanto la expresión anterior se menciona que el trabajo mecánico es igual a los cambios de energía cinética del sistema mecánico. Trabajo mecánico y energía potencial. ... "Se realiza un trabajo sobre un cuerpo cuando este se desplaza o deforma por la acción de una fuerza" (definición de trabajo).
It's the node of the standing wave.