Which of the following describes a positive feedback loop? O When blood sugar concentration is too low, the endocrine system secretes hormones that increase blood sugar concentration to a normal level.
O When the body senses that the heart rate is very high, it secretes hormones that decrease the heart rate.
O When blood sugar concentration is too high, the endocrine system secretes hormones that decrease blood sugar concentration to a normal level.
O When someone is exercising intensely, the body secretes hormones that increase oxygen supply for cellular respiration.​

When someone is exercising intensely, the body secretes hormones that increase oxygen supply for cellular respiration.​

Explanation:

Positive feedback is defined as the reaction in nature in which the product of reaction increases. A positive feedback loop is not limited to a level but can move away from the equilibrium.

For example: During intense exercising, heart started producing more oxygen or pumps blood faster through the body.

Hence, the correct answer is "4.​"

the answer is A when blood sugar contraction is to low

Explanation:

i took the test

there is no stairs in bungalow

explanation:

poof

substitution is the answer in this case