Question

Ans me 65 number i will mark as brainliest
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Answer 1

a) Yawning (oscitation) most often occurs in adults immediately before and after sleep, during tedious activities and as a result of its contagious quality. It is commonly associated with tiredness, stress, sleepiness, boredom, or even hunger. ... During a yawn, the tensor tympani muscle in the middle ear contracts.

b) When we are sleepy or feel drowsy, we yawn because our brain cells lack sufficient amount of oxygen. The deep breath associated with yawning helps us to drawn in more oxygen and supply the much needed oxygen to the tired body organs including the brain..