Animals with radial symmetry get information

a. from sense organs concentrated in their heads.

b. from all directions.

c. from specialized nerve cells in their brains.

d. from motor neurons.

A. From sense organs concentrated in their heads.

Explanation:

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Since animals with radial symmetry have body parts arranged around a central point, they have lines of symmetry.  Due to the circular assortment of their parts, radially symmetrical animals do not  have distinct front or back ends but they have a central head, that's why they must focus their senses into the head to get information.

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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.