The correct option is A i-3, ii-1, iii-2, iv-4
Haemoglobin is an iron-containing pigment protein that gives blood its red colour. It exists in a quaternary structure composed of two α- chains and two β -chains (α 2 β 2).
Keratins are fibrous proteins present in eukaryotes. They can occur as helical ⍺-keratin or β-keratin. In vertebrates, almost the entire dry weight of hair, wool, feathers, nails, horns, hooves and the majority of the outer skin layer occur as α-keratin.
Glycine is the simplest amino acid where the R group is hydrogen. It is a non-essential amino acid as it can be synthesised by the body.
Valine is an aliphatic essential amino acid in humans.