Final answer:
Cardiac and skeletal muscles share a striated appearance; skeletal muscles are under voluntary control while cardiac muscles are involuntary.
Step-by-step explanation:
Cardiac and skeletal muscles have a striated appearance in common. Striated muscles show a pattern of light and dark bands under the microscope due to the arrangement of their protein filaments. This is feature (b) from the options provided. However, there are differences between these two muscle types. Skeletal muscles are under voluntary control, meaning they can be consciously controlled by an individual's will, which matches option (a). In contrast, cardiac muscles operate involuntarily without conscious thought, aligning with option (c). Therefore, striated appearance is the feature that both cardiac and skeletal muscles share.