GMAT Sentence Correction (SC) | Re: In 1979 lack of rain reduced India's rice production to

Correct Answer: In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent less than the 1978 harvest.

If there were options,
1) In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent less than that of 1978.
2) In 1979 lack of rain reduced India's rice production to about 41 million tons, nearly 25 percent less than that of the harvest in 1978.

Would they both be correct? If no, what is wrong with these sentences?

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