The statements that are TRUE:
(A) Methane leads to both global warming and photochemical smog.
(B) Methane is generated from paddy fields.
(C) Methane is a stronger global warming gas than CO?.
(D) Methane is a part of reducing smog.
Choose the most appropriate answer from the options given below:

Insulin is a globular proteins.

Primary structure of protein in unaffected by physical or chemical changes.

For stabilization of a - helix structure of protein, H-bonding is responsible which is in between  group present in protein.

In proteins, the secondary structure (such as α-helices and β-sheets) is stabilized by hydrogen bonds formed between the carbonyl oxygen of one peptide bond and the amide hydrogen of another.

Linear: N? (azide ion)

Bent-shape: O? (ozone), NO? (nitrite ion), Cl? O (dichlorine monoxide)