Muscle tissue may be stimulated by which of the following?

Muscle tissue can be stimulated by electric current because this type of stimulation involves the application of electrical impulses that can trigger muscle contractions. The human nervous system operates using electrical signals, which allow muscles to receive commands to contract and relax. This process is especially relevant in various medical and therapeutic environments where electrical stimulation is used to promote muscle function, rehabilitation, or even in advanced techniques like neuromuscular electrical stimulation (NMES).

While sound waves, magnetic fields, and inhaled chemicals may have some influence in specific contexts, they do not directly stimulate muscle contraction in the same straightforward way that an electrical current does. Therefore, electric current is the most appropriate and accurate choice for the stimulation of muscle tissue.