Dehydration reactions are necessary for the formation of ?
a) monomers. b) polysaccharides. c) monosaccharides. d) bonded carbon atoms.

Dehydration reactions are needed for the synthesis and or formation of B. Polysaccharides. This is because during these reactions monomer or simple molecules and or compounds are combined with other similar monomers, in this case monosaccharides to produce a polysaccharide, each time a covalent bond occurs between the monomers, the H from one monosaccharide and an OH group from another come off and form water as a result. So basically during the synthesis, water is removed and or "dehydrated" from the reaction.

The answer would be sand and gravel