1. Monazite is a source of rare earths.
2. Monazite contains thorium.
3. Monazite occurs naturally in the entire Indian coastal sands in India.
4. In India, Government bodies only can process or export monazite.

Explanation : 

Monazite as a Source of Rare Earth Elements

Monazite is indeed a source of rare earth elements, which are critical for a variety of modern technologies. It is a phosphate mineral that contains thorium, a radioactive element, as well as rare earth elements. Therefore, statements 1 and 2 are correct.

Occurrence of Monazite in Indian Coastal Sands

Statement 3 is not entirely accurate. While monazite does occur in coastal sands, it is not found along the entire Indian coastline. It is mainly found in the heavy mineral sands of the beaches of Kerala, Tamil Nadu, and Odisha. Therefore, it is incorrect to say that monazite occurs naturally in the entire Indian coastal sands.

Mining and Processing of Monazite in India

Statement 4 is correct. In India, the mining and processing of monazite are restricted and can only be carried out by government or government-authorized entities due to its thorium content, which has strategic importance as a nuclear fuel. The Atomic Minerals Concession Rules, 2016, under the Atomic Energy Act of 1962, regulate the mining and handling of monazite.

Thus, the statements 1, 2, and 4 are correct, making the correct answer: 1, 2, and 4 only.