This is the body's ability to function effectively and effeiceintly without unduefatigue

Blue it is beautiful

Natural is correct i hope i could you out

J. vincent scarpace makes fish art and if you look it up its very beautiful work. his original work can be found in private or public places in 40 different countries.
he is now retired, but he still makes his unique fish art. he refers to his art as " a personal journey through the use of basic of art elements; line, shape, and colors - resulting in works of art which purposely resemble fish. " 

The answer is letter d.