IMO A
In C,D and E you don't need 'and' to separate the sentences. And makes it sound as if Barbera Wootton is telling two things
A) that there was an elephant who used to give rides and B) that the elephant used to earn exactly what she was earning.
Plus in D 'was earning annually exactly what she then earned as director of adult education for London' is not an independent clause.
Same for E that it earned....is not an independent clause.
So we come down to B and A.
In B giving is incorrect, since we don't know if the elephant is still giving rides, plus shes quoting an incident from the past, so the use of simple past tense (gave) is fine
IMO A.