Which one among the following causes stomach pain in human body?

The human stomach naturally produces hydrochloric acid to facilitate the digestion of proteins and eliminate harmful bacteria [3]. Under normal conditions, a layer of mucus protects the stomach lining from this corrosive acid [3]. However, during indigestion, the stomach produces an excessive amount of acid, which leads to irritation and pain [1]. This condition, often referred to as acidity, causes discomfort that is typically treated with antacids—mild bases like magnesium hydroxide or sodium hydrogencarbonate—which work by neutralizing the excess acid [4]. While certain bacteria like Helicobacter pylori can cause inflammation and ulcers that lead to pain, the primary chemical agent directly responsible for the burning sensation and irritation in the context of common gastric distress is the acid itself [6]. Therefore, excess acid is the fundamental cause of stomach pain in the human body.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > pH in our digestive system > p. 27
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85
3. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > Stomach > p. 125
4. [4] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Uses of Baking soda > p. 31
5. [6] https://pmc.ncbi.nlm.nih.gov/articles/PMC3149864/