Which of the following are not extremophiles? a. pompeii worms b. bacteria in boiling hot springs c. fish living in open oceans d. fish living in water below freezing

The correct answer would be c. fish living in open oceans.

Extremophiles refer to the organisms which are able to survive in extreme conditions such as high temperature, high pressure, high salinity et cetera.

For example, Pompeii worm is an extremophile which is usually found at hydrothermal vent, Picrophilus torridus is a thermoacidophile that is, it can survive in hot and acidic conditions et cetera.

Fish living in open oceans do not face such extreme conditions, thus, they are not the example of extremophile.

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