What are the different types of substations?

I - Elevating substations are used to raise generation voltages to transmission voltage values.
II - Reducing substations reduce transmission voltage levels to subtransmission or distribution levels.
III - Link substations are used for electrical systems that require greater operational flexibility to increase service continuity and reliability.
IV - Ring substations are frequently used in distribution systems to interconnect substations that are interconnected with others.
V - Radial substations have a single power supply point and are not interconnected with others.
VI - Switching substations do not have a power transformer since it is not necessary to modify the voltage level of the power sources, and only connection and disconnection operations are performed.
a) I, II, III, IV, V and VI are correct.
b) I, II, III, IV and V are correct.
c) II, III, IV, V and VI are correct.
d) I, II, III, IV and VI are correct.