The phospholipid is composed of a glycerol molecule and tow fatty acid chains. The phospholipid is an amphiphatic molecule having hydrophobic tail and hydrophilic head. The fatty acid chains are uncharged and non-polar while the phosphate head is polar and negatively charged. The phospholipid molecules forms micelles when placed in water.
Hence, the correct answer is 'a glycerol molecule between two fatty acid chains'.