The passage explains that Japan has a tradition of short tenures for Prime Ministers, with 38 leaders coming and going during Emperor Hirohito’s reign.
This frequent turnover has fostered a political environment where the ruling Liberal Democratic Party (LDP) functions through factionalism.
Faction leaders play a key role in deciding the next party chief and Prime Minister, often through bargaining rather than public elections.
Option (a) — no mention is made of urban–rural interest clashes as the main cause of factionalism.
Option (b) — the long reign of the Emperor is stated as a fact but is not connected to the cause of factionalism.
Option (c) — fears of one-man leadership are mentioned in relation to Eisaku Sato’s long tenure, but this was addressed by term limits, not cited as the main driver of ongoing factionalism.
Thus, (d) is correct because frequent leadership changes create opportunities and necessity for factional negotiations.