The correct answer is B. isomeric.
Isomers are compounds that have the same molecular formula but different structural formulas. They have the same number and type of atoms, but the atoms are arranged differently.
For example, butane and 2-butene have the same molecular formula, $C_4H_{10}$, but different structural formulas:
- Butane: $H_3C-CH_2-CH_2-CH_3$
- 2-Butene: $H_3C-CH=CH-CH_3$
Isomers can be classified into two types: structural isomers and stereoisomers.
Structural isomers have different bonding patterns. For example, butane and 2-butene are structural isomers.
Stereoisomers have the same bonding pattern but different arrangements of the atoms in space. For example, enantiomers are stereoisomers that are mirror images of each other.
Isomers can have different physical and chemical properties. For example, butane is a gas at room temperature, while 2-butene is a liquid.
Isomers can be important in organic chemistry because they can have different biological activities. For example, the isomers of testosterone have different effects on the body.