Final answer:
Hormonal changes leading to sebum overproduction and keratin accumulation result in blocked hair follicles, creating an environment for bacterial growth which causes the inflammation and redness associated with acne.
Step-by-step explanation:
The increased occurrence of acne in the phase 2 study can be attributed to a variety of factors, primarily hormonal changes which lead to the overproduction of sebum. This overproduction, coupled with the accumulation of keratin, can block hair follicles, creating a plug that provides the perfect environment for acne-causing bacteria such as Propionibacterium and Staphylococcus to thrive. When these bacteria infect the blocked follicles, it results in inflammation, characterized by redness, swelling, and in some cases, pus and potential scarring, all of which are hallmark symptoms of acne.