Define transverse Tubules

Define transverse tubules.

A) Transverse tubules forms a tubular network around each individual myofibril and is similar to the smooth endoplasmic reticulum of other cells.
B) Transverse tubules are composed primarily of actin filaments.
C) Transverse tubules are composed primarily of myosin filaments.
D) Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum.
E) Transverse tubules are tubular proteins that bind calcium within the sarcomeres.