Carbon is found in all living organisms. The constant flow of carbon on Earth through organisms and the air is
known as the carbon cycle. absorb carbon from the atmosphere in the form of carbon
dioxide. They use it for respiration and . Animals consume plants, transferring carbon
along the food chain. Plants and animals respire and release carbon into air. When the animals and plants
die, they are eaten by . Carbon enters back into the atmosphere in the form of
.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.