Sentence Correction (SC) | Re: On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited

Hello,
I need some help here.
This is how I see the original sentence:
On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited the planet Mars and succeeded in its mission to contribute to Martian atmospheric studies, and [mapping Martian surface features from the lowest possible altitude, it detected heat sources from Martian volcanoes in search of evidence of recent volcanic activity].

"mapping...altitude" acts as modifier of "it detected heat sources from Martian volcanoes in search of evidence of recent volcanic activity". Since it mapped the surface feature from lowest possible altitude, it was able to detect heat signatures. This reasoning also seems plausible.
", and" acts as a correct separator of two independent clauses.

Though other choices are grammatically correct, they change the meaning of the original sentence.
So i would prefer A to other choices.

Could anyone explain the error in my reasoning?

Regards,
Ankit

Statistics : Posted by Anandanwar • on 06 Aug 2015, 10:42 • Replies 16 • Views 8559

---