Which pair of statements best describes an essential amino acid? a. it is an amino acid that contains peptide bonds. an example is proline. b. it is an amino acid that contains nitrogen. an example is aspartic acid. c. it is an amino acid that cannot be made by the body. it must be obtained from eating certain foods. d. it is an amino acid that can be produced by the body. vitamin supplements maintain healthy levels.

Which of the following types of stars is most likely to end up as a supernova? in graph a, the curve peaks at 800 nm, in the red section of the visible light spectrum. in graph b, the curve peaks at 550 nm, in the green section of the visible light spectrum. in graph c, the curve peaks at 450 nm, in the blue section of the visible light spectrum. in graph d, the curve peaks at 300 nm, in the violet section of the visible light spectrum. a b c d