I assume there should be a list of choices included in this question. Since there are none given, I will give examples of powers delegated to the states.
In the Constitution, some powers are set aside for the federal government. Only the federal government has certain powers, which are called the enumerated powers. Some powers are set aside only for the states, which are called the reserved powers. The state and the federal government share some powers, which are called the concurrent powers.
The reserved powers are the ones set aside only for the state government. These include making decisions regarding education within a state, determining punishments for crimes for breaking state laws, and determining trade policies within a state. The state government, not the federal government, would determine education policy within a state. The number school days that exist in a school year is a decision made at the state level. The same is true for what the punishments would be for breaking a state law. The reserved powers are those set aside for the state government.