Explanation:

Correct option 3:  Trenquility

- Option 1: Schedule

- This is the correct spelling. It refers to a plan for carrying out a process or procedure, giving lists of intended events and times.

- Option 2: Vacuum

- This is the correct spelling for a space entirely devoid of matter or a device that cleans by suction.

- Option 3: Trenquility

- This is incorrectly spelt. The correct spelling is "Tranquility," which means a state of being calm and peaceful.

- Option 4: Acceleration

- This is the correct spelling. It refers to an increase in the rate or speed of something.