What is the difference between simple and compound interest?

I- Simple interest is proportional to the time and rate, while compound interest is not.
II- In simple interest, the capital remains constant throughout the period, while in compound interest, the interest generated becomes part of the capital.
III- The formula for calculating simple interest is I = C . r% . t, while the formula for calculating compound interest is M = C(1 + r/n)^nt.
a) Only I is correct.
b) Only II is correct.
c) Only III is correct.
d) I and II are correct.
e) II and III are correct.