Choose the incorrect statement

the generation of suprathreshold endplate potentials in multiple muscle fibers could be due to the increased frequency of action potential generation at the axon hillock of a single motor neuron.
propagation of an action potential through the t-tubules into the sarcoplasmic reticulum triggers the release of ca++ into the cytoplasm of a skeletal muscle fiber.
a very small amount of ach would be found in the neuromuscular synapse after exposure to botulinum toxin, which blocks the formation of the snare complex proteins.
the motor end plate membrane is only capable of generating graded potentials, but it is contiguous with the skeletal muscle sarcolemma, which can generate action potentials.

The incorrect statement is: The motor end plate membrane is only capable of generating graded potentials, but it is contiguous with the skeletal muscle sarcolemma, which can generate action potentials.

The motor end plate membrane generates threshold potential-"All or None" potential.  After the release of acetylcholine from the presynaptic neuron, it diffuses across the neuromuscular junction and binds to its receptors on the muscle fiber. As a result conductance of sodium and potassium is increased which results in depolarization of the muscle cell membrane. This is called a miniature end-plate potential (MEPP) which is additive meaning that it leads to a greater depolarization of the postsynaptic membrane and become end plate potentials (EPPs).  

it is either c or d and i know for sure it is not a or b