Haemoglobinic Acid Formation Statements

Steps:

• Identify haemoglobinic acid as the product of hemoglobin reacting with acids, forming acid hematin.
• Evaluate statement 1: It correctly describes the protonation of hemoglobin's heme groups in acidic conditions.
• Evaluate statement 2: It accurately notes the role of chloride ions in stabilizing the acid form.
• Evaluate statement 3: It properly explains the color change to brown due to denaturation.

Why A is correct:

• All three statements align with the biochemical definition of haemoglobinic acid formation via protonation and denaturation of hemoglobin.

Why the others are wrong:

• B excludes 3, but statement 3 is valid on color change.
• C includes only 1, ignoring valid 2 and 3.
• D excludes 1, but statement 1 is essential to the reaction.

Final answer: A