A hypothesis is a 1.) tentative answer to a question. 2.) possible solution. 4.) proven theory. 5.) a stronger term for certainty than a theory.

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.

i'd have to say the answer is probable the second option "the geosphere interacting with the atmosphere"