Final answer:
Reza's original political motive was to challenge the shah of Iran's policies favoring foreign oil interests. He introduced progressive reforms and sought to nationalize Iran's oil fields.
Step-by-step explanation:
Reza's original political motive was to challenge the policies of the shah of Iran, Muhammad Reza Shah Pahlavi, who was favorable to foreign oil interests.
Reza's motive was progressive in nature, as he introduced reforms such as public housing and social security. He intended to pay for these programs through the nationalization of Iran's oil fields, which greatly concerned US and British business interests.