Concept:Ginkgo is a tree species that has remained almost unchanged for millions of years, so it is called a living fossil.Explanation:Ginkgo trees date back about 200 million years.Their present form has not changed for 51 million years.Scientists studied preserved leaves and reproductive organs and found very little change in over 100 million years.This lack of change over such a long time is similar to a fossil, but the tree is still alive, hence the name 'living fossil'.Answer:Living fossil (Option A)