The correct options are
A Forts offered protection from attacks.
B Forts showcased the power and might of rulers.
C Forts enabled rulers to control people, land and trade.
D Forts enclosed capital city and involved lot of planning.
Mahajanapadas had capital cities and these cities were fortified. Forts served various purposes as it offered protection from attacks by other rulers. Building impressively huge forts also showcased the might of rulers. It also facilitated the ruler to control the land and people living inside the fortified area. Building forts involved lot of planning about the use of resources.