The correct answer is true.
It is true that the long-term and short-term carbon cycles are connected by the fact that some of the carbon contained in C6H12O6 (or other organic molecules) in plants is incorporated into sedimentary rocks or oil; it is not immediately reintroduced back into the atmosphere.
The carbon cycle refers to the flow of carbon in oceans, rocks, atmosphere, and biosphere. The short term carbon cycle is very important because it recycles carbon. It operates in hundreds of years. Carbon sinks such as tropical forest stores carbon in a temporary way. It is in the long term cycle that real carbon sinks operate.