Correct option is A
Option (a) is the correct order of the given sentences.
Explanation of correct order:
C starts the paragraph: "Many successful people believe that..." → This introduces the main idea.
D completes C: "...there is no failure in anybody’s life." → completes the belief being discussed.
A adds an explanation: "They think there are some bitter learning experiences..." → elaborates what is meant by ‘no failure’.
B concludes: "Which, over a period of time, guide them to take a good path." → describes the outcome of those learning experiences.