Which type of muscle tissue does not have striations?

Smooth muscle is the correct answer because it is characterized by the absence of striations. The muscle fibers in smooth muscle are spindle-shaped and arranged in a non-striated manner, which distinguishes them from skeletal and cardiac muscle.

Skeletal muscle contains clear striations due to the regular arrangement of actin and myosin filaments, which allow for voluntary movement. Cardiac muscle, while also striated, has a unique structure that includes intercalated discs allowing for synchronized contraction of the heart. Striated muscle is a broad term that typically refers to both skeletal and cardiac muscle, but does not apply to smooth muscle. Therefore, smooth muscle's lack of striations is what makes it the correct answer in this context.