Task: Instance Description Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes the instance 'railway spine'?

A. An outdated and offensive diagnosis which posited that not all transgender people are "truly" transgender (or transsexual). Sometimes used and shortened to "trutrans" by some transgender people who wish to elevate themselves above other trans people for any of various reasons.
B. A nineteenth-century diagnosis for the post-traumatic symptoms of passengers involved in railroad accidents.
C. A lesbian sexual practice in which a woman rubs her vulva against her partner's body for sexual stimulation, especially for stimulation of the clitoris. This may involve vulva-to-vulva contact or rubbing the vulva against the partner's thigh, stomach, buttocks, arm, or other body part (excluding the mouth).
D. A former diagnostic label previously given to transgender people who experienced significant dysphoria. The term was dropped and replaced with gender dysphoria in DSM-5. The condition was renamed to remove the stigma associated with the term disorder. The phrase "gender identity disorders" appeared some time before 1980, with one of the earliest being in 1972, although it was almost certainly coined before that, it is unknown who originated the term.

Answer: A nineteenth-century diagnosis for the post-traumatic symptoms of passengers involved in railroad accidents.