What typically causes second-degree heart block, Mobitz type I?

Factors that affect our posture include:

a. long-term habits b. emotional state c. health/wellness d. all of the above

Which connective tissue divides the thoracic cavity into two pleural cavities and encloses the heart?

A) Mediastinum B) Pleural sac C) Pericardial sac D) None of the above