The discovery of what properties of neurotransmission caused neuroscientists to rethink Dale’s Principle?

3.co-release and cotransmission of more than one neurotransmitter

Explanation:

The complete question is as follows:

The discovery of what properties of neurotransmission caused neuroscientists to rethink Dale's Principle?

inhibition of neural activityneural communication at more than one place at a neuronco-release and cotransmission of more than one neurotransmitterfinding similar neuronal activity in more than one location in the brainDale's principle was given by a scientist named Henry Dale in 1940's and the principle state that each neuron is capable of releasing only a single type of neurotransmitter.This principle meant that a particular neuron is capable of performing only a single function at all the synapses.However, Dale's principle were soon proven to be false when it was discovered that there are many neurons capable of releasing more than one neurotransmitter at a time and this is termed as cotransmission and co-release of the neurotransmitters. An example of co-transmission is the release of GABA along with substance P as cotransmitter.

Distillation.  distillation is the correct answer.