What Have Recent Studies on Panic Attacks Concluded

What have recent studies on panic attacks concluded?

A) Beliefs about controllability showed no correlation to panic attacks
B) Perceived uncontrollability of panic symptoms play an important role in panic attacks
C) Having a safe person nearby the individual prone to panic attacks does not impact panic attacks
D) 50 percent of people who believed they had no control over the carbon dioxide had a panic attack while only 50 percent who believed they could control the carbon dioxide experience had a panic attack