Question

Qual estar incorreta?

Since September 11th, american scientists studied the health of search-and-rescue dogs that nosed through the debris at ground zero, but so far, they have found no signs of major illness in them.
A) nosed through
B) but so far
C) illness in them
D) studied the health

Answer 1

Alternativa d. studied the health

Como o colega já falou, o certo é usar o present perfect ([...] American scientists have studied the health [...]) aqui.