Of the Following Examples, Which One Demonstrates a Common Barrier

Of the following examples, which one demonstrates a common barrier to improving human thinking?

A) Krystal is a person who carefully examines every decision using controlled thinking.
B) Jokan is a person who balances how often he uses automatic and controlled thinking when considering decisions.
C) Ben is a person who is often too optimistic about the accuracy of his judgments.
D) Miguel is a person who is realistic about his thinking but lacks confidence in his decisions.