The correct answer that would best complete the given statement above would be option A. An ecosystem is defined as the interrelationship between living beings and the environment. It is a community wherein organisms interact with each other as well as to their physical environment.
If these substances become dissolved in the water vapour present in the air then acid rain can form. Acid rain can corrode and kill trees (damaging animal habitats) and wear away older buildings such as those made of limestone.
The answer would be in a spiral arm. The spiral arms are then region of the stars being extended from the spiral's center and the barred spiral galaxies. The region which is a long and thin one looks like a spiral and so the name spiral galaxy is given.
