Please explain

We are told that even though the southern Levant and the northern Levant had similar climates, the southern Levant was abandoned about 6,000 years ago while the northern Levant was not. Archaeologists hypothesized that the southern Levant was abandoned 6,000 years ago due to an economic collapse that resulted from deforestation. We must take these statements and the archaeologists' hypothesis to be true and pinpoint the answer choice that, on the basis of the above being true, therefore, cannot be true. So, answer choice (D) cannot be true because it states that before 6,000 years ago, there were no forests present in the southern Levant. But, if we are to take the archaeologists' hypothesis to be true, we know that there were forests prior to 6,000 years ago and then deforestation occurred, which led to an economic collapse resulting in depopulation. Thus, since there must have been forests prior to 6,000 years ago, answer choice (D) cannot be true. Hope that clears things up! Please let us know if you have any other questions.