Male peacocks have tail feathers that make up 60% of their body length. during the mating season they fan their tails and shake these feathers in front of females. females evaluate the tail-shaking behavior as part of selecting their mate. which of the behaviors below is most likely to have been the original behavior that, through natural selection, resulted in this mate choice behavior of tail shaking?

1. flight
2. head movement to make eye contact
3. sound production with the larynx
4. involuntary muscle contraction like shivering
5. grooming feathers with the beak

Choose the incorrect statement (a) 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. (b) 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. (c) 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. (d) a greater amount of ach would be found in the presynaptic vesicles of a motor unit that fired several action potentials after exposure to botulinum toxin, than in a motor unit that fired several action potentials after exposure to the venom of the krait snake (which contains α-bungarotoxin).