Which step ONLY occurs in the formation of coal?

a. movement of the earth causes the rock to fold and form a trap.

b. decaying swamps are covered with seawater.

c. organic remains are trapped under layers of sediment and water.

d. great temperatures build-up over layers of organic material.

"Decaying swamps are covered with seawater" step ONLY occurs in the formation of coal.

Option: B

Explanation:

Coal production continues in regions of swampy wetlands because groundwater is near to or just above the topsoil. Because of this, organic matter is created quickly by the flora present-faster even than it can be broken down. Layers of organic matter are deposited in these areas, and then buried.

Based on the plants and circumstances present, the mechanism that produces coal varies somewhat in various areas but the ultimate method is similar. Coal production has two primary phases: peatification, and coalification. It is a solid black, readily combustible fossil fuel containing a large quantity of carbon-based material-about 50 percent of its mass.

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.