A table made entirely from the trunk of a tree said to have lived a thousand years was recently claimed to be that of a

Premise: A table made entirely from the trunk of a tree said to have lived a thousand years was recently claimed to be that of a much younger tree.

Conclusion: In order to rebut this charge, the craftsman summoned a team of dendrochronologists to prove that the tree lived to be at least to 1,000 years old.

So, we want to examine the options to see which can serve as the assumption of this passage.

Option A - Incorrect:
The other works of art produced by the artist are not the subject matter of consideration in this passage. So, this assumption holds no strong point.

Option B - Incorrect:
We cannot be so sure about this assumption because the number of years the tree lived before it was cut down was not stated in the passage. It could have lived less or more than 1000 years before cutting it down, we can't be so sure. However, we can still deduce that the tree has lived more than 1000 years because a table that has lived 1000 years was made from its trunk.

Option C - Incorrect:
This is out of context with respect to the passage.

Option D - Correct:
For each passing year, a tree develops exactly one ring, as seen in a horizontal cross-section of the trunk. In addition to validating the passage conclusion from my point of view assumption, if the table made from the trunk of the tree has lived 1000 years; this means that the tree in question has lived at least 1000 years. So, we can easily assume that the wood used in the table is large enough to contain a span of one thousand tree rings.

Option E - Incorrect:
Of course, the dendrochronology approach is only accurate for trees that lived less than 2000 total years, and this validates this claim ("Dendrochronology has shown to be inaccurate for the oldest trees in the world"). However, this doesn't build an assumption to make the passage conclusion a reality (i.e .... summoned a team of dendrochronologists to prove that the tree lived to be at least to 1,000 years old.).