Free SH group is present in
High-Yield Explanation
This is a tricky question. Option a, b and c have sulphur. But, only cysteine contains SH group. EXTRA EDGE:- Sulphur containing amino acids: Cysteine Methionine Homocysteine Taurine Sulfhydryl/thiol group-containing amino acids: Cysteine Homocysteine Sulfhydryl/thiol group-containing proteinogenic amino acids: Cysteine