SCIENTISTS REVEAL THREE KEYS TO HAPPINESS PART B: Which detail from the text best supports the answer to Part A?

A
“To make your way down the road to happiness you need to feel competent and believe that you can make a difference. You also need to understand what the heck is going on around you and have the opportunity to choose your own options.” ( Paragraph 2)
B
“But the Kaplans were intrigued by one study that came out about that time suggesting that what people really liked in their lives was a ‘medium level of complexity.’" ( Paragraph 7)
C
“In a series of studies, the couple demonstrated that an office window that overlooks a natural scene helps people relax, thus fighting off one of the primary threats to competence, mental fatigue.” ( Paragraph 24)
D
“But wouldn't a debilitating disease like cancer be so overwhelming that it would wipe out the three conditions the Kaplans feel are so important?” ( Paragraph 29)