The cell membranes in skeletal muscle

The cell membranes in skeletal muscle
A. Are impermeable to fat-soluble substances.
B. Are more permeable to sodium than to potassium ions.
C. Become more permeable to glucose in the presence of insulin.
D. Become less permeable to potassium in the presence of insulin.
E. Show invaginations which connect to a system of intracellular tubules involved in excitation contraction coupling