Good morning.
We see that

The magnitude(norm, to be precise) can be calculated the following way:

Now the calculus is trivial:
Answer:
The correct answer is - Damage to the nerves that control the diaphragm.
Explanation:
Abdominal breathing is a condition in which inferior half of the lungs can be seen relaxing or contracting and expanding with the breath. This condition occurs due to the various conditions that lead to the respiratory.
It is cause due to the damage to nerves that control the diaphragm. The phrenic nerve is one of the nerve of diaphragm initiates in the neck and passes down.
Thus, the correct answer is - Damage to the nerves that control the diaphragm.
The phrenic nerve is a nerve that originates in the neck (C3–C5) and passes down between the lung and heart to reach the diaphragm.
The coil is rotated rapidly in the magnetic field.
The magnetic flux linked with the coil changes and thus, an emf is induced which leads to the flow of current .
when the coil rotates and is in a position along the direction of the magnetic field, emf is maximum while when it is perpendicular to the magnetic field,emf is 0.
Thus an ac generator converts mechanical to electrical energy.It works on the principle of electromagnetic induction. The polarity at the supply terminals changes like.. 100 times a second if the frequency is 50 Hz(50 times+ and 50 times - )
hope it helps!