For Pm=(Ad/Ld)*K, which of the following is true?

• A. Pm=mean effective pressure
• B. Ad and Ld are area of diagram and length of diagram respectively
• C. K id the indicator spring constant
• D. *K, which of the following is true?a) Pm=mean effective pressureb) Ad and Ld are area of diagram and length of diagram respectivelyc) K id the indicator spring constantd) all of the mentioned