prep sc, temperature of the globe and temperature in Alaska

[LinqingJ930]

According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees.

(A) the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees
(B) the surface temperature in Alaska, Siberia, and northwestern Canada has increased over the last thirty years by about five degrees
(C) there was an increase in the last thirty years by about five degrees in Alaska, Siberia, and northwestern Canada
(D) it had increased in Alaska, Siberia, and northwestern Canada by about five degrees over the previous thirty years
(E) it has increased in Alaska, Siberia, and northwestern Canada over the previous thirty years by about five degrees

The answer is B. However I'm confused about A. Is "In the previous thirty years" is also suitable in the present perfect tense? and why A is wrong? or A is not wrong but B is better?

[RonPurewal]

"In" isn't acceptable, but for reasons much too subtle to be relevant on this test.

This one is pretty straightforward:
"- The non-underlined part contains "over the last century".
"- You need to choose a construction to express an exactly analogous statistic for the last 30 years.

So... you make it parallel.
A is parallel.
B isn't.
Done.