**Core Concept**
Botulinum toxin is a potent neurotoxin that acts by inhibiting the release of acetylcholine at the neuromuscular junction, thereby causing flaccid paralysis of the affected muscle. Its therapeutic applications are based on this mechanism of action.

**Why the Correct Answer is Right**
Botulinum toxin is used for the treatment of various conditions characterized by excessive muscle contraction or spasm. Blepharospasm, also known as eyelid spasms, is a condition where the eyelids twitch or spasm, causing discomfort and visual disturbances. Risus sardonicus, also known as facial spasm, is a condition where the facial muscles contract involuntarily, causing a characteristic smile-like appearance. Strabismus, or crossed eyes, is a condition where the eyes are misaligned due to an imbalance in the extraocular muscles. Botulinum toxin injections into the affected muscles can temporarily relax them, alleviating symptoms in all these conditions.

**Why Each Wrong Option is Incorrect**
**Option A:** While botulinum toxin is indeed used for blepharospasm, this option does not encompass the full range of conditions treated with this toxin.
**Option B:** Although botulinum toxin can be used for facial spasms, risus sardonicus is a more specific condition, and this option is too narrow in scope.
**Option C:** Strabismus is a condition that can be treated with botulinum toxin, but this option does not account for the other two conditions listed.

**Clinical Pearl / High-Yield Fact**
Botulinum toxin has a long history of use as a bioterrorism agent, and its potential for misuse is a significant concern in forensic medicine. Awareness of its therapeutic applications and potential for abuse is essential for medical professionals and forensic experts.

**✓ Correct Answer: D. All**