Indicate whether each of the following descriptions better applies to cardiac (C), skeletal (K), myoepithelial (M), or smooth (O) muscle cells. Your answer would be a four-letter string composed of letters C, K, M, and O only, e.g. MMKC.
( ) They are derived from the ectoderm layer, similar to epithelial cells.
( ) They form the lining of cavities such as the urinary bladder.
( ) They are responsible for most voluntary muscle movements.
( ) They form multinucleated and exceptionally long muscle fibers.