Final answer:
The combining form 'Ichthy/o' refers to 'dry, scaly'. An exoskeleton provides a hard covering for protection and muscle attachment. A dolphin has a fusiform shape, streamlined for efficient movement in water.
Step-by-step explanation:
The combining form that refers to "dry, scaly" is Ichthy/o. This form is derived from the Greek word 'ichthys' which means fish, referencing the dry, scaly appearance of fish skin. It is commonly used in medical terms related to skin conditions that have a dry, scaly texture, such as ichthyosis. The other options listed do not denote 'dry, scaly': Myc/o refers to fungi, Pil/o to hair, and Adip/o to fat.
A hard covering or shell that provides protection and muscle attachment is called an exoskeleton (option c). Organisms such as insects and crabs have exoskeletons. Finally, an organism that has a fusiform shape, which means a tapered shape at both ends, is a dolphin (option b). This shape is typical for aquatic animals that need to move through water efficiently.