The correct answer is - Merchants and conquerors.
Islam was spread in India in both, peaceful manner, but also forcefully.
The Islam first came to India in the 7th century through Arab and Persian merchants, and it started to spread out along the coastal regions of Malabar and Gujarat as Muslims started to settle in those regions and create communities. Soon after, the first mosque was also built.
In the 12th century, Northern India was invaded by the Moguls (turko-mongolic people) who were practicing the Islam, and as they spread out their influence, they also started to convert people into Islam, often against their will, so a large population of Muslims in the northern part of India arose during their occupation.
