Of the following, identity the system you would find in a human, but not in a flatworm.

a nervous system
a digestive system
a respiratory system

a respiratory system

Explanation:

i took the test and it was right

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.