Final answer:
The correct answer is D) phospholipids, which are major constituents of cell membranes, possessing hydrophobic and hydrophilic properties important for forming the lipid bilayer.
Step-by-step explanation:
The lipids found in the membranes of all eukaryotic cells are D) phospholipids. Phospholipids are essential components of cell membranes and are composed of two fatty acid chains attached to a glycerol or sphingosine backbone. The third component on the backbone is a phosphate group modified by an alcohol, such as choline. This gives phospholipids an amphipathic character, with both hydrophobic (water-repelling) and hydrophilic (water-attracting) properties, which enables the formation of the lipid bilayer in cell membranes.
While other lipids, such as triglycerides, waxes, and steroids are present in living organisms, only phospholipids play a central role in the structure of the plasma membrane. Furthermore, cholesterol is another lipid component of the eukaryotic plasma membrane, which helps to maintain the membrane's fluidity and is the precursor to steroid hormones like testosterone.