**Answer:**

The correct answer is option 'b) Communist Party of India'.

**Explanation:**

**1. Marxism-Leninism:**
Marxism-Leninism is a political ideology that combines the theories of Karl Marx and Vladimir Lenin. It is a variant of Marxism that specifically focuses on the ideas and strategies of Lenin, who was a Russian revolutionary and the leader of the Bolshevik Party during the Russian Revolution.

**2. Communist Party of India:**
The Communist Party of India (CPI) is a political party in India that adheres to the principles of Marxism-Leninism. It was founded in 1925 and is one of the oldest political parties in India. The CPI aims to establish a socialist society in India through revolutionary means.

**3. Beliefs and Principles:**
The Communist Party of India believes in the following principles:

- **Class Struggle:** The party believes in the concept of class struggle, where the working class must overthrow the capitalist class to establish a socialist society.
- **Socialism:** The CPI believes in the establishment of a socialist society where the means of production are owned and controlled by the working class.
- **Revolutionary Change:** The party believes in the need for revolutionary change to bring about a socialist transformation of society.
- **Anti-Imperialism:** The CPI opposes imperialism and seeks to align with other communist parties and progressive movements internationally.
- **Democratic Centralism:** The party follows the principle of democratic centralism, which means that decisions are made democratically within the party, but once a decision is made, it must be followed by all members.

**4. Other Political Parties:**
a) Nationalist Congress Party (NCP): The NCP is a political party in India that was founded in 1999. It is a centrist party that does not have Marxist-Leninist beliefs.

c) Dravida Munnetra Kazhagam (DMK): The DMK is a regional political party in the state of Tamil Nadu in India. It is a Dravidian party that focuses on regional issues and does not have Marxist-Leninist beliefs.

d) Bahujan Samaj Party (BSP): The BSP is a political party in India that represents the Bahujans, which include Scheduled Castes, Scheduled Tribes, and Other Backward Classes. It is a social justice party that does not have Marxist-Leninist beliefs.

Therefore, the political party that believes in Marxism-Leninism is the Communist Party of India (CPI).