Voltage, V = IR
Where I is current in Ampere, R is Resistance in Ohms.
V = 9A * 43 Ω
V = 387 V
Because you would fall so slow that you would not need one.
what happens at Point C is sublimation. the increase in temperature affects the Vapour pressure soon as you can see the curve is increasing with increasing pressure there is increase in temperature that is the sublimation Curve
Considering the unknown resistence as R and using the Ohm's First Law, we have:
The equivalent resistence is given by the resistor series with the lamp resistence.

If you notice any mistake in my english, please let me know, because i am not native.