**Core Concept**
Active osteosclerosis, also known as otosclerosis, is a type of bone remodeling disorder in the middle ear that leads to hearing loss. It is characterized by abnormal bone growth in the bony labyrinth, specifically in the stapes bone. This abnormal growth causes fixation of the stapes bone, resulting in conductive hearing loss.

**Why the Correct Answer is Right**
The correct answer is associated with the pathophysiology of otosclerosis. In active otosclerosis, the abnormal bone growth can cause the stapes bone to become fixed, leading to a decrease in the mobility of the ossicles. This decreased mobility results in a decrease in the transmission of sound waves to the inner ear, ultimately causing hearing loss. The tympanic membrane, being a part of the ossicular chain, is affected indirectly by the fixation of the stapes bone.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the color of the tympanic membrane in active osteosclerosis. The color change is not the primary manifestation of otosclerosis.
**Option B:** This option is incorrect because it is not the typical color change associated with active osteosclerosis. The correct answer is more closely related to the underlying pathophysiology of the condition.
**Option C:** This option is incorrect because it does not accurately describe the color of the tympanic membrane in active osteosclerosis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that otosclerosis is a progressive condition that can lead to hearing loss if left untreated. Early detection and treatment, often involving hearing aids or surgical intervention, can help manage the condition and prevent further progression.

**Correct Answer:** C.