Cellular receptors may be composed of Select one: a. combinations of any or all of the above. broteins. carbohydrates. d. lipids.

To solve this problem, we need to analyze the options provided regarding the composition of cellular receptors. 1. **Understanding Cellular Receptors**: Cellular receptors are proteins that receive and transmit signals from outside the cell to the inside. They can interact with various types of molecules, including proteins, carbohydrates, and lipids. 2. **Analyzing the Options**: - **a. combinations of any or all of the above**: This option suggests that cellular receptors can be made up of proteins, carbohydrates, and lipids. - **b. proteins**: This option states that cellular receptors are made solely of proteins. - **c. carbohydrates**: This option states that cellular receptors are made solely of carbohydrates. - **d. lipids**: This option states that cellular receptors are made solely of lipids. 3. **Conclusion**: Since cellular receptors can indeed be composed of proteins, carbohydrates, and lipids, the most comprehensive and accurate answer is: **a. combinations of any or all of the above.** This option reflects the complexity and diversity of cellular receptors in biological systems.