Select the true statements about protein secondary structure.
A. In a β‑pleated sheet, the side chains extend above and below the sheet.
B. The secondary level of protein structure refers to the spatial arrangements of short segments of the protein.
C. Disulfide bonds stabilize secondary structure. In an α‑helix, the side chains are located inside the helix.
D. The α‑helix is held together by hydrogen bonds between the amide N − H and C = O groups.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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