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Answer: (A) sacroiliac joints
Explanation:
Reactive arthritis can be define as a condition which is associated with the inflammation of joints specifically the sacroiliac joints and joints of the lower body. This occurs due to the infection in an area other than the joints. The joint inflammation is characterized by swelling, warmness in and around the joints, redness and pain. Additional symptoms include inflammation of the urinary tract, inflammation of the lines of the eyelids and eye membrane, fever, pain in lower back and heel, and weight loss.
This is caused by the bacterial infection belonging to the genus of Campylobacter, Shigella, Salmonella, Chlamydia and Yersinia.
I think the smallest but impactful act is to just support local farmer's markets.
The least likely explanation for this would be that they're training at different intervals, or one is training harder than the other.
The most likely reason is that the way the other person's genetics are most people cant gain muscle as well as others because of disease or their body structure.
Hope this helped!
I think it the answer is B