Lassaigne's test is a qualitative test in analytical chemistry used to detect the presence of certain elements, namely nitrogen, sulfur, and halogens in an organic compound. The test involves heating the organic compound with sodium metal to convert these elements to sodium salts, which can then react with specific reagents to yield visibly identifiable compounds.

Let's go through the options one by one:

Option A suggests that Lassaigne's test is used for the detection of phosphorous and halogens only. This is incorrect because the test is also used to detect nitrogen and sulfur.

Option B suggests that the test is for nitrogen, sulfur, and phosphorous only. However, Lassaigne's test does not typically involve a specific test for phosphorous.

Option C, which is the correct answer, indicates that this test is used to detect nitrogen, sulfur, phosphorous, and halogens. Even though phosphorous detection isn't as common as the detection of nitrogen, sulfur, and halogens in the typical Lassaigne's test, the option stating all four elements should be considered the most complete answer among those provided, given its inclusion of all elements that could potentially be detected with adaptations of the test.

Option D states that the test is for nitrogen and sulfur only, which is not entirely accurate because the test can also be used to detect halogens, and potentially, albeit less commonly, phosphorous.

Therefore, the most accurate answer is Option C: Nitrogen, Sulphur, phosphorous, and halogens.