What physical feature blocks access to the Indian subcontinent to its north and northeast? I believe it is the Himalayas, but I'm not sure.

It would be The Himalayan Mountain Range Because it would be the range of the Himalayan

The correct answer is - the Himalayan Mountain Range.

The Himalayan Mountain Range, is a natural border that occurs on the north and northeastern part of the Indian subcontinent. This mountain range is the most massive, and the highest in the whole world. It was formed as a result of the collision of the Indian tectonic plate with the Eurasian tectonic plate, and since both plates are continental plates, and have the same density, the land started to lift up in height because of the sheer force and pressure by the collision. The Himalayas are still growing in height and size nowadays, and this trend will continue for the foreseeable future.