In C program language please.

(Factorial) The factorial of a nonnegative integer n is written n! (pronounced "n factorial") 3.45 and is defined as follows: n! = n - (n - 1) (n - 2) . ... 1 (for values of n greater than or equal to 1) and n! = 1 (for n = 0). For example, 5! = 5.4.3.2.1, which is 120. %3D a) Write a program that reads a nonnegative integer and computes and prints its factorial. b) Write a program that estimates the value of the mathematical constant e by using the formula: 1. e = 1+ 1! 2! 3! c) Write a program that computes the value of by using the formula =1+ 1! 2! 3! +-+