Which of the following is used to determine a person's DNA sequence?

Genes are segments of DNA that encode the information for making proteins.

The sequence of nucleotides (As, Ts, Cs, and Gs) in a gene determines the amino acid sequence of the protein. DNA sequencing is the process of determining the sequence of nucleotides in a piece of DNA.

Choice A is incorrect because enzymes are proteins that catalyze chemical reactions, not DNA sequences. Choice B is incorrect because blood types are determined by the presence or absence of certain antigens on the surface of red blood cells, not by DNA sequences. Choice C is incorrect because hormones are chemical messengers that regulate various body functions, not DNA sequences.

Melanin is a pigment produced by cells called melanocytes in the skin.

It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.

This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.

Choice B. Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.

Choice C. Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.

Choice D. Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.