Answer:
The spike will remain at 3-feet above the ground in 30 years time because the spike does not increase in height as the tree does.
Please find the explanation below
Step-by-step explanation:
Living things including the trees stated in this question are capable of growth (in height and girth). According to this question, a spike is hammered into a tree base at 3-feet above the ground level. However, after 30 years, the tree grows to 100 feet but the spike will remain at 3-feet above the ground.
This is because the spike, which is naturally incapable of growth, will not grow alongside the tree. A plant (tree) undergoes growth at its apices or meristem i.e. the tree will elongate from the tip and not any other part. Hence, the tree will grow and leave the spike at its initial level.