Which of the following conditions relates to a sac-like structure accumulating fluid specifically in the scrotum?

The condition that pertains to a sac-like structure accumulating fluid specifically in the scrotum is a hydrocele. A hydrocele occurs when there is an abnormal accumulation of serous fluid in the tunica vaginalis, which is the thin pouch that surrounds the testicle. This condition can be present at birth or develop later, often without an obvious cause, and typically presents with swelling or a palpable mass in the scrotum that is usually painless.

In contrast, pleural effusion involves fluid accumulation in the pleural space surrounding the lungs, while hydrothorax is a specific kind of pleural effusion resulting from fluid accumulation in that same area. Hematocele refers to the accumulation of blood in the scrotal cavity, often due to trauma or injury, rather than fluid. Therefore, hydrocele is the specific condition associated with fluid buildup in the scrotum, distinguishing it from the other conditions listed.