Canadian scientists have calculated that one human being should be struck every nine years by a meteorite,
while each year sixteen buildings can be expected to sustain damage from such objects.
(A) one human being should be struck every nine years by a meteorite
(B) a human being should be struck by a meteorite once in every nine years
(C) a meteorite will strike one human being once in every nine years
(D) every nine years a human being will be struck by a meteorite
(E) every nine years a human being should be struck by a meteorite

I was confused between D & E.

since the original sentence said should I selected E. OA is D.

how can we know what the intention of the original sentence is.

The OG explains it in a different way saying that should is more of a moral obligation as if every human deserves to be struck.

However, I was thinking of it in terms of certainty vs uncertainty.

Someone pleas explain, when should is interpreted in terms of uncertainty and when in terms of obligation or not. Or are both same??