The function of choke is to provide high voltage enough for 
ionization to take place in a tube light and after 
establishment and substenance of ionization, limit the 
voltage across the tube. That is the reason why a tube 
fuses when the choke is shorted.

The choke acts a regulator and controls the current flow
thro' the flourescent tube.

At the time of starting a tube choke gives rise to high 
voltage by di/dt nearly 1000 volts by starter ON-OFF 
function rate of change of voltage becomes high due to 
inductance of choke. This high voltage starts ionization of 
gas in the tube. Once gas gets ionised and starts 
conducting then starter gets out of circuit and circuit is 
completed only through choke which now share voltage(limit 
voltage) for tube because after esabilishing ionization now 
to maintain it only nearly half of the voltage is required.

To start the tubelight. we have to ionise the gas inside 
tubelight like murcury which ionise at high voltage around 
1000 to 1500 V it is provided by choke.

It is used to provide high voltage approximately 1000 to 
1500 Volt.

Choke(Ballast)provide a High voltage which is required for 
ionisation of particles og tube light(approx.)-600 volt and 
after this limit the current

answer 3 is very correct

choke is highly inductive , so it opposes any sudden change 
of voltage . 
At start it stores electrical voltage and passes it with 
high amplitude within sec(1000-1200V) for ionisation of 
gases in tube bar .