• A body with pointed ends is referred as the streamlined body. Fishes and birds have streamlined bodies.
• A  streamlined body gives a smooth surface to the sea animal's body which lessens obstruction in the water by decreasing friction and makes development simple. 
• The least resistance in water speeds up the movement, organisms move at a quicker speed. Having a  streamlined body is a transformation or, more specifically, a development to assist the organisms in surviving in a better way.
• Aeroplanes and ships' bodies are also streamlined to reduce the resistance due to air and water.

Hence, option B is the correct answer.