Non-metallic minerals in India are best described as:

Correct Option: Abundant and essential for key sectors

Explanation:

Non-metallic minerals are minerals that do not contain metallic elements in their raw form and do not yield new products on melting. India is endowed with a rich variety of non-metallic mineral resources, such as limestone, mica, dolomite, phosphate, gypsum, and granite.

These minerals play a crucial role in several key industrial sectors:
1. Limestone: Essential raw material for the cement industry, iron and steel smelting (used as a flux), and chemical manufacturing.
2. Mica: Highly valuable in the electrical and electronic industries due to its excellent insulating properties and resistance to high voltage.
3. Phosphate & Gypsum: Vital for fertilizer production and agriculture, supporting national food security.
4. Dimension Stones: Granite and marble contribute significantly to construction and export revenue.

Thus, non-metallic minerals in India are best described as abundant and essential for key sectors, driving basic infrastructure, manufacturing, and industrial expansion across the economy.