What is the value of V^1?

Actually Welcome to the Concept of the Current Electricity.

Since here, A potential divider is setup with two resisters in series, that is 3 ohm and 6 ohm.

As the voltage is always in directly proportional to the resistance,by ohm law,

V = IR, so the increase in Voltage will lead to increase in the resistance too.

hence,

for 6 ohm the voltage is 4 V, then for the 3 ohm it would be ,

V1 = (4/6)*3

==> V1 = 2 Volts,

==> hence the potential V1 = 2V

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

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-- soprano singer

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-- tenor singer

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since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.