The correct option is (b).
Explanation
Muscle tissues in animals are classified into three distinct types based on their structure and function: Skeletal, Smooth, and Cardiac muscles. These types differ significantly in their microscopic appearance (presence of striations), mechanism of control (voluntary vs. involuntary), and cellular structure (nucleation).Statement-wise Analysis
- Statement 1 is Incorrect. Smooth muscles are non-striated. They lack the visible cross-bands or striations that characterize skeletal and cardiac muscles, giving them a "smooth" appearance under a microscope. The term "striated muscles" typically refers to skeletal muscles.
- Statement 2 is Correct. Smooth muscles are involuntary in nature, meaning they are not under conscious control. They are regulated by the autonomic nervous system and are responsible for movements in internal organs, such as the peristaltic movement of food in the alimentary canal and the contraction of blood vessels.
- Statement 3 is Incorrect. Smooth muscle cells are spindle-shaped (fusiform) and are uninucleate (possessing a single central nucleus). It is the skeletal muscle fibers that are multinucleate (syncytium).
Key Takeaway: Smooth muscles are defined by being involuntary, non-striated, and uninucleate. They are primarily located in the walls of hollow visceral organs like the stomach, intestine, and urinary bladder.