Mid ocean ridges normally form where tectonic plates are
a. converging
b. diverging
c. stationary
d. sliding past each other

Mid ocean ridges are formed when the two plates are pulled apart, due to the power of the convection current. lava flows through this newly formed gap and reacts with the water above, forming rock. Leaving an underwater mountain range (the answer is b, sorry for a late response!) 

There can be more freedom for them

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast.