Hi,
The product obtained is an alkene named as ethene CH2=CH2, ethanol produces ethene on dehydration by reaction with conc. H2SO4 so, the compound A is ethanol CH3CH2OH.
The reactions are:
CH3CH2OH --H2SO4--> CH2=CH2 + H2O
conc. H2SO4 acts as catalyst and dehydrating agent.
Regards