The correct answer is (c) Low temperature, high pressure.
Explanation: To liquefy a gas, like natural gas, both low temperature and high pressure are needed. When a gas is cooled down and compressed, the molecules slow down and get closer together, allowing them to transition into a liquid state.
Why other options are incorrect:
(a) Low temperature, low pressure:
Low temperature alone slows down the molecules, but without high pressure to bring them closer together, they won’t be able to form a liquid.
(b) High temperature, low pressure:
High temperature actually speeds up the molecules, making it harder to liquefy them, even with high pressure.
(d) High temperature, high pressure:
While high pressure alone can partially compress a gas, the high temperature counteracts the effect of compression, preventing liquefaction. High temperature increases the kinetic energy of the gas molecules, making them move further apart rather than closer together.