Maleic acid and fumaric acid are \[A)\]Position isomers $B)$Geometric isomers $C)$Enantiomers $D)$Functional isomers
Hint: Maleic acid is an organic compound which is a dicarboxylic acid (molecule with two carboxyl groups). The molecule consists of an ethylene group flanked by two carboxylic acid groups. Maleic acid is the cis isomer of butenedioic acid, whereas fumaric acid is a trans isomer.
Complete answer: Maleic acid and fumaric acid are geometrical isomers. Geometrical isomerism is possible when different groups are attached to the double bonded carbon atoms. The two most common types of geometric isomers are those arising from a double bond and those arising from a ring structure. These type of geometric isomers are also called cis or trans isomers. When two identical groups occupy adjacent positions, the isomer is called cis isomer. Maleic acid is otherwise known as cis-butenedioic acid, which has a double bond that is flanked by two carboxylic acid groups. Maleic acid, a geometric isomer, is thus a diastereomer and therefore a stereoisomer. An important distinction to make here is that maleic acid is the cis isomer, whereas fumaric acid is the trans isomer. So, the correct option is $B)$ Geometric isomers.
Note: Fumaric Acid can affect you when breathed in. Contact can irritate and burn the skin and eyes. Breathing Fumaric Acid can irritate the nose and throat causing coughing and wheezing. Fumaric Acid may damage the kidneys.