The answer is reflexes. Reflexes are usually involuntary muscle movements that happen almost instantaneously in response to stimuli. A reflex is made possible by neural pathways called reflex arcs which can act on an impulse before that impulse reaches the brain. It is a survival mechanism evolved by the body used in the objective to escape danger.
The first one is the right answer
The correct answer is option (B) lemon juice.
pH refers to the logarithmic scale used to indicate the acidity or basicity of an aqueous solution. It is the negative of the base 10 logarithm of the activity of the hydrogen ion. Solutions with a pH less that 7 are considered acidic and the solutions with a pH greater that 7 are considered to be basic. A pH of 7 is neither an acid nor a base and is considered neutral.
An acid has a high concentration of hydrogen ions (H+) and a base has a low concentration of hydrogen ions. Higher the hydrogen ion concentration, pH is acidic. Among the given substances, lemon juice has a pH of 2, urine has a pH of 6, tomato juice has a pH of 4 and black coffee has a pH of 5. Since lemon juice has a pH of 2, it has the lowest –OH ion concentration.
I think it’s b or c, sorry I’m not sure which one! Hope this is helpful
