In the context of modern scientific research, consider the following statements about 'IceCube', a particle detector located at South Pole, which was recently in the news:1.It is the world's largest neutrino detector, encompassing a cubic kilometre of ice.2.It is a powerful telescope to search for dark matter.3.It is buried deep in the ice.Which of the statements given above is/are correct?

1. A

   1 only

   (a) 1 only. IceCube is the world’s largest neutrino detector, using about a cubic kilometre of Antarctic ice, but it is also buried deep and used in dark-matter searches. 1 only is incomplete.

2. B

   2 and 3 only

   (b) 2 and 3 only. Dark-matter search and burial in ice are correct, yet omitting the cubic-kilometre neutrino-detector fact drops statement 1, which is true.

3. C

   1 and 3 only

   (c) 1 and 3 only. Size and burial are right, but IceCube is also used as a powerful instrument in the search for dark matter. Dropping 2 is wrong on this key.

4. D

   1, 2 and 3

   (d) 1, 2 and 3. IceCube instruments a cubic kilometre of ice at the South Pole, is buried deep, detects neutrinos, and is used in dark-matter searches. All three statements are treated as correct; that is the official key.

Summary. Official key is (d) 1, 2 and 3. IceCube is a cubic-kilometre neutrino observatory buried in South Pole ice and is also used to search for dark matter. None of the three statements is rejected on this paper. The keyed answer is the full set.