Final answer:
The assertion that invaders reached India through western mountain passes, such as the Khyber Pass, is true; this facilitated the spread of Islam and the formation of the Delhi Sultanate.
Step-by-step explanation:
The statement that invaders were able to reach India through passes in the western section of the mountains is true. The famed Khyber Pass, located between Pakistan and Afghanistan, has been historically significant as a gateway for various invasions into the Indian subcontinent. Notably, this pass facilitated the entry of Islam into northern India, leading to the establishment of the powerful Delhi Sultanate. Despite India's mountainous geography, which includes the imposing Himalayas to the north, the Khyber Pass and other such passes allowed for the movement of peoples and the exchange of cultures and religions throughout history.