Which choice best describes data from the table that weaken the stude…

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In agriculture, tilling is the process of preparing soil by mechanical agitation, such as digging or stirring. A student reviewing recent agricultural research claims that tilling soil universally benefits crop production. Specifically, the student hypothesizes that crop yields will always be higher in tilled fields compared to untilled (no-tilling) fields, regardless of the farming environment. The provided table summarizes the results of three independent studies measuring crop yields under both methods.

Which choice best describes data from the table that weaken the student's claim?

There are some studies, such as the study by T.K. Das and colleagues, that have found crop yields to be lower with tilling than without it.

The finding that tilling is associated with an increase in crop yield has not been replicated outside of Croatia.

The study by Bogunovic and colleagues actually found that tilling was associated with a decrease in crop yield rather than an increase.

Vinicius Brown and colleagues reported a crop yield of 3,070 kilograms per hectare when no tilling was used but a yield of only 2,270 kilograms per hectare when tilling was used.