The main reason for the deteriorating condition of the peasants in the late 1920s and early 1930s, which led to peasant movements in Punjab, Gujarat, and Uttar Pradesh, was the fall in the prices of primary commodities. This means that the prices of agricultural products, such as crops and livestock, were declining during this period.

Option 1 - New settlement: This option is not the main reason for the worsening condition of the peasants during this time. New settlement refers to the allocation of land or settlement of new areas, which may have had an impact on peasants but is not directly related to their worsening condition.

Option 2 - Oppression of the landlords: While oppression of landlords may have contributed to the difficult situation of the peasants, it is not the main reason for their worsened condition. Other factors, such as economic and market conditions, played a more significant role.

Option 3 - Rent regulations: Rent regulations usually aim to protect the rights and interests of tenants. While the absence of rent regulations may have affected the peasants` condition, it is not the primary reason for their worsening condition.

Option 4 - Fall in the prices of primary commodities: This is the correct answer. The decline in the prices of agricultural products directly impacted the income and