Answer:
• election records with information reflecting disagreements among government leaders.
• documents discussing legislation by those in power.
Explanation:
Since the historian is looking to study the political causes for a particular city's rapid development, the types of historical records that the historian can research for this task include:
• election records with information reflecting disagreements among government leaders
• documents discussing legislation by those in power.
In this case, the historian can check the election records to know if the disagreement among the government leaders brought about the rapid development.
Also, the documents discussing legislation by those in power can show if there was a certain legislation that has an impact on the development.