Acid Rain is the problem threatening many of Europe's (most specifically Germany's) forests, lakes, and rivers. Acid rain travels via the wind and the acid pollutants can travel through this said wind to multiple countries. It was a large problem in the 1970's and 80's.
You're gonna have to give us a picture to support your question..
The answer is:
Echinodermata
The word echinodermata is Greek which literally means "Spiny Skin". Echinodermata is a phylum under kingdom animalia. Not all of them have spiny skins, but most of them do. Other characteristics would be their radially symmetric body. They have appendages that grow outward from the center. Examples of echinoderms would be sea stars and sea urchins.
B. Histones is the correct answer.