Texto para a questão.

(Unipê-Medicina)
Harvesting organs from animals may provide the solution to the shortfall of human donors. However, two technical obstacles need to be overcome before animal-human transplants can become a medical reality. One is that human immune systems often reject foreign tissue. The second problem comes from the risk of disease transfer.

According to George Church of Harvard Medical School, genetically engineering pigs may provide the key to overcoming this second problem. Due to their size, pigs are natural candidates for animal-human transplants, but their DNA is naturally rife with dangerous PERVs, or porcine endogenous retroviruses. An innovative gene-editing technique known as CRISP has the capacity to identify and delete specific sequences out of the genome. Upon discovering that a single porcine gene enables PERVs to infect human hosts, Dr. Church and his colleagues turned CRISP against the culprit. Initial results suggest that this procedure may be a success, preventing human infection without compromising the pig cells.

HARVESTING. Disponível em: . Acesso em: 13 maio 2018. Adaptado.

Na frase do primeiro parágrafo “However, two technical obstacles need to be overcome [...]” , a palavra however:

A
indica conclusão e poderia ser substituída, sem mudança de sentido, por Therefore.

B
indica condição e poderia ser substituída, sem alteração de significado, por As long as.

C
equivale, em português, a Como se diz habitualmente.

D
pode ser traduzida como Portanto.

E
poderia ser substituída, sem mudança de sentido, por Nevertheless.