Which is not considered one of the four major oceans?

The answer is the Antarctic ocean.

Explanation:

The International Hydrographic Organization established that the fifth ocean in the world was the Antarctic ocean, also known as the Southern Ocean. This ocean surrounds all the Antarctica.

The largest oceans in the world are: the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean followed by the Antarctic ocean.

According to a publication made by the International Hydrographic Organization in 2000 called "Limits of Oceans and Seas," the Antarctic ocean was the fifth in the world.  

i would say b probably

answer; /// i do believe the correct answer is ( a