"El abogado ha demostrado lo contrario."
Translation:The lawyer has proved otherwise.
shouldn't lo contrario translate to "it otherwise". I think "The Lawyer has proved it otherwise" should be marked correct.
With a helping verb (ha) I think it would call for the past participle (proven). and contrario also means the opposite.
It doesn't make any sense to use ha in a lesson where literally every other use of the verb comes in as the past perfect.