The peloponnesian war began after
sparta attacked athens by land.
sparta attacked athens by sea.
athens attacked sparta by land.
athens attacked sparta by sea.
the answer is : sparta attacked athens by land.

Sparta attacked Athens by land.

You must note that the war was started by Sparta, and that Sparta had a better army, while Athens had a better navy. Since Sparta initiated the war, they were usually able to choose whether the battles would mostly be on land or in the sea. Sparta acted on them having a better land force, and invaded through land, which led to Sparta's victory.

~

the caste system in india is the paradigmatic ethnographic example of caste. it has origins in ancient india, and was transformed by various ruling elites in medieval, early-modern, and modern india, especially the mughal empire and the british raj.it is today the basis of educational and job reservations in india.it consists of two different concepts, varna and jati, which may be regarded as different levels of analysis of this system.

the caste system as it exists today is thought to be the result of developments during the collapse of the mughal era and the british colonial regime in india. the collapse of the mughal era saw the rise of powerful men who associated themselves with kings, priests and ascetics, affirming the regal and martial form of the caste ideal, and it also reshaped many apparently casteless social groups into differentiated caste communities.the british raj furthered this development, making rigid caste organisation a central mechanism of administration

i didn’t fully understand your question but i hope this you !