LPG consists of mainly:

LPG is a clean fuel that is extensively used in homes as a gas for the central heating system and in kitchens for cooking. Typically, it comes from wet natural gas or petroleum. The majority of its components are lighter hydrocarbons.

Known as LPG, liquefied petroleum gas is a fuel. It contains a variety of hydrocarbons. LPG is often produced by refining petroleum or extracting wet natural gas from reservoirs. Crude oil can also be used to extract it.
Methane (CH₄), butane (C₃H₈), and propane (C₄H₁₀) make up the majority of LPG. Other gases included in LPG besides methane, butane, and propane include isobutane, ethane, ethylene, propylene, butylene, and isobutylene.

LPG is a clean fuel since it produces fewer byproducts. In the current context, it has taken the position of chlorofluorocarbons, a greenhouse gas that damages the ozone layer.
LPG weighs a lot more than air as well.
Therefore, at relatively low pressures, may be easily compressed into a liquid.

Hence, the correct option is (D).