The correct increasing order of pH found in the human body is option 1: Gastric juice, saliva, blood.

pH is a measure of acidity or alkalinity in a solution, with values ranging from 0 to 14. A pH of 7 is considered neutral, below 7 is acidic, and above 7 is alkaline or basic.

Gastric juice, which is found in the stomach, has a pH ranging from 1 to 3. This low pH is due to the presence of hydrochloric acid, which helps in the digestion of food.

Saliva, which is produced by the salivary glands in the mouth, has a pH ranging from 6.2 to 7.6. It is slightly acidic to neutral and helps in the breakdown of food particles and the initial stages of digestion.

Blood, which circulates throughout the body, has a slightly alkaline pH ranging from 7.35 to 7.45. Maintaining a stable pH of the blood is crucial for proper functioning of the body`s cells and organs.

Therefore, the correct increasing order of pH found in the human body is gastric juice (pH 1-3), saliva (pH 6.2