Which one of the following is a product of dehydration reaction

During dehydration in Kreb’s cycle two molecules of citric acid by losing two molecules of water, is changed into two molecules of another 6-carbon compound cis-aconitic acid. It is catalyzed by aconitase. During dehydration in glycolysis by the activity of enolase, two molecules of 2-phosphoghycerate is converted to two molecules of phosphoenolpyruvate (PEP).