Is lowest at the axon hillock since there is the least loss of current at this point  due to summation

Is lowest at the dendrites where current can sum

Is lowest at the axon hillock where there is the highest density of voltage-gated Na⁺ channels

Is lowest at the dendrites since there is the least loss of current at this point 

Is lowest at the dendrites where there is the highest density of voltage-gated Na⁺ channels