So the answer should be D right?

That's what I got too.

A table made entirely from the trunk of a tree said to have lived 1,000 years was recently claimed to be made from that of a much younger tree. In order to rebut this charge, the craftsman summoned a team of dendrochronologists to prove that the tree lived to be at least 1,000 years old. Dendrochronology, or the technique of using tree rings to date wood, is based on the fact that for each passing year a tree develops exactly one ring, as seen in a horizontal cross-section of the trunk. Given that dendrochronology is accurate for trees that lived less than 2,000 total years, the dendrochronologists will be able to determine whether the work comes from a tree that lived to be at least 1,000 years old.
A. The craftsman has not used the trunk of the same tree in other works of art he has produced.
The passage did not mention about the craftsman's other crafts from this same tree.
B. The tree was not less than 1,000 years old when it was cut down.
This is the conclusion of the passage.
C. The craftsman worked on the wood consistently, without taking breaks of more than one year.
The passage did not mention how long it would take to complete the table.
D. The wood used in the table is large enough to contain a span of 1,000 tree rings.
Answer. The author assumed that the table has at least 1000 rings, otherwise the conclusion that the table is at least 1000 yrs old would not be true.
E. Dendrochronology has shown to be inaccurate for the oldest trees in the world, since parts of the trunks are so worn down that traces of tree rings are difficult to discern.
If Dendrochronology is inaccurate, the conclusion is rendered wrong.