Sentence Correction (SC) | Re: QOTD: Twenty-two feet long and 10 feet in diameter, the AM-1

Twenty-two feet long and 10 feet in diameter, the AM-1 is one of the many new satellites that is a part of 15 years effort of subjecting the interactions of Earth's atmosphere, oceans, and land surfaces to detailed scrutiny from space.

That refers to satellites.
Effort to is correct idiom.
15-year is correct.

A. satellites that is a part of 15 yearseffort of subjecting the interactions of Earth's atmosphere, oceans, and land surfaces

B. satellites, which is a part of a 15-year effort to subject
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