Answer: 4
The mechanical advantage is the ratio of the force exerted by the object to the force applied to do work on it.
Here, Jeff tried to lift a rock weighing 600 pounds by wedging board under the rock. Jeff who weighs 150 pounds uses all his weight to exert force on lever and lift rock.
Mechanical advantage, 
Therefore, the mechanical advantage that lever provided to Jeff in lifting rock is 4.
Answer:
you will be the clouds
and I will be the sky.
you will be the ocean
and I will be the shore.
you will be the trees
and I will be the wind.
whatever we are, you and I will always collide.
There you go! Let me know if it helped.
:)
The amount of solid does not affect how you are describing the solid so a is the answer
C: if it senses unequal currents