Bombay became prime city of india in the following ways1) In the 17th century, Bombay was a group of seven islands under Portuguese control.2) In 1661 , control of islands passed into british hands after the marriage of Britain's King Charles ll to the Portuguese princess.3) The East India Company quickly shifted it's base from Surat to Bombay.4) At first, Bombay was the major outlet for cotton textiles from Gujarat. 5) Later , in the 19th century, the city functioned as a port and later it became an important administrative and industrial centre.

Introduction:
Bombay, now known as Mumbai, became the prime city of India due to various factors. The city was a small fishing village until the 17th century, after which it became the center of trade and commerce. Today, it is considered the financial capital of India and the country's largest city.

Factors that led to Bombay becoming the prime city of India:
1. Strategic Location: Bombay is located on the west coast of India, making it an ideal location for trade and commerce with other countries. The city's deep natural harbor played a significant role in making it a major port city.

2. British Rule: The British East India Company took over Bombay in 1661 and developed it as a trading post. The city grew rapidly under British rule, with the construction of infrastructure such as railways and roads.

3. Economic Opportunities: Bombay's location and infrastructure led to the growth of various industries such as textiles, shipping, and banking. The city became a hub for trade and commerce, attracting people from all over the country.

4. Cultural Diversity: Bombay has been historically known for its cultural diversity, with people from various parts of India and the world settling in the city. This led to the growth of various communities and cultural institutions, making the city a melting pot of different cultures.

5. Political Importance: Bombay played a significant role in India's struggle for independence. The Indian National Congress held its first session in Bombay in 1885, and the city was also the site of major political events such as the Quit India Movement in 1942.

Conclusion:
In conclusion, Bombay became the prime city of India due to its strategic location, British rule, economic opportunities, cultural diversity, and political importance. These factors led to the city's rapid growth and development, making it the financial and cultural capital of India today.