I would say letter A to this because we need rain water for crops plants. Also we need it so that we can drink it. Its less great over sea because as it merge with the salt in the ocean it becomes less drinkable and less usable.
It is based on atomic number, which is the number of protons in the nuclei of the atoms of an element.
B is the correct answer hope that helped
Answer:
a) 
b) 
c)
d) 
Explanation:
Given:
- mass of the astronaut,

- vertical displacement of the astronaut,

- acceleration of the astronaut while the lift,

a)
<u>Now the force of lift by the helicopter:</u>
Here the lift force is the resultant of the force of gravity being overcome by the force of helicopter.

where:
force by the helicopter
force of gravity


b)
The gravitational force on the astronaut:



d)
Since the astronaut has been picked from an ocean we assume her initial velocity to be zero, 
using equation of motion:



c)
Hence the kinetic energy:


