Question

Concerning the verb tense in “They have called on scientific journals”, it's correct to say about that: *

the present perfect is used because the action is happening at this moment.
the present perfect could also be used because the action happened at some unknown point in the past.
the present perfect is used because the action happened at some unknown point in the past.

Answer 1

Resposta:

the present perfect is used because the action happened at some unknown point in the past.

Explicação:

Esta é a maior característica do Present Perfect: ação ocorrida no passado mas em um tempo indefinido ou desconhecido.