Hi Ron
I am not sure whether the subordinate clause introduced by "although" must have a subject and a verb. I recalled that it isn't the case for some OG questions.
However, in SC question 17 of OG13, the offical instruction get rid of C and D using the above rule. This confuses me.
My reasoning to get rid of C and D is basd on the meaning: It is not logical to say that you cannot see something on the pole/equator, but that thing is visable on the surface. As we know, surface includes pole/equator. Hence, the meaning of A is logical.
Could you please share how you get rid of C and D?
Thank you!
Michael