Sentence Correction

can anyone explain me NASA problem and my doubt below please

pops wrote:me too at 80%

[spoiler]
I went wrong on Nasa's space mission question.
I thought "previously estimated" is incorrect. When we are using estimated, its obvious that it was estimated before. so I chose the choice which doesn't have 'previously estimated' and it went wrong
[/spoiler]

Notice that Choices A and B have at least one grammatical error.

Choice A - they is used for collective noun NASA
Choices A and B - SV pair does not make sense.

If you replace the pronoun with the antecedent the sentence now implies -

Nasa will start decelerating Orion and return home soon.

Nasa return is non-sensical in the context of this sentence.

Also, previously estimated may not be considered as redundant expression as the engineers at NASA may have just done the estimation when they found that the satellite went deeper that they expected.

@rsadana1

Can you tell me how to review the previous quiz ?