Meaning of 'go over' and 'go on'

[Tonys]

Test No. incompl/elem-22 "Weather Forecast", question 1

Now let's go ......... to our weather forecaster, Mary.

(a) on
(b) out
(c) over
(d) against

Test No. incompl/elem-22 "Weather Forecast", answer 1

Now let's go over to our weather forecaster, Mary.

Correct answer: (c) over

Your answer was: incorrect
Now let's go on to our weather forecaster, Mary.
_________________________

Why the answer is "over" insted of "on"?

thank you
Tonys

[Alan]

Hi,

The sentence reads: