Answer: Option B
:
B
Down the group ionization enthalpy decreases with an increase in atomic size.
Along theperiod it increases due to an increase in effective nuclear charge and decrease in size.
K > Na > Li ---> same group, going upwards ---> so decreasing
Be > Mg > Ca ----> same groupbut going downwards, so it should increase.
B > C > N ---> same period, going left to right ---> so increasing
Ge > Si > C ----> same group, going upwards. ---> so decreasing