Which statement best describes the ocean floor

Initially, people's believe about the ocean floor was that it is mostly flat, and that it has little to no distinguishing features. This was proven wrong when sonar was used to map the ocean floor by German scientists in the early 20th century, and they observed that the ocean floor is varied and it showcases such distinguishing features as atolls, submarine canyons, and mid-ocean ridges.

A,) cause a & b are equal & both gives 180°