Part 1. Definition
In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
Part 2. Example
In early work , Rutherford discovered the concept of radioactive half-life, the radioactive element radon, and classified three types of radiations: alpha, beta and gamma radiation .

Answer: Rutherford discovered the radioactive half-life, the chemical element radon, and the three parts of radiation which he named Alpha, Beta, and Gamma .

Explanation: The output sentence is a simplified version of the input sentence.
Part 3. Exercise
The thoracic diaphragm , or simply the diaphragm , is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity .
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The diaphragm is a muscle that is at the bottom of the ribcage of mammals .