What are 3 submarines that made it deep into the ocean?

Answerglycogen;

Ithink its d.stratum

It's probably because the earth is actually tilted and is not straight when orbiting the sun. that's why when it's winter here, it's summer in the southern hemisphere. in the wintertime in the northern hemisphere, it's colder here because it's tilted away from the sun and the southern hemisphere is tilted closer to the sun (i believe this is the case anyways)

Iam pretty sure that the answer is either a. -  it would the ecosystem become more stable. or it is d. -  the larger number of species would make the ecosystem more prone to disease.. 
i would go with d.
i hope this you!
have a nice day!