The correct option is D C>Si>Ge>Sn>Pb: Order of I.E.
(A) Dut to inert pair effect, the stability of +2 oxidation state as we move down the group increases.
(B) As we move down the group, electronegativity decreases. Hence, acidic order decreases.
(C) Down the group the size increases and electronegativity decreases, and, thereby, tendency to show catenation decreases.
(D) Correct order of I.E. : C > Si > Ge > Sn < Pb
As we move down the group, the I.E. decreases, due to increase in atomic size, thereby, increasing the distance of e from nucleus. The first I.E. of Pb is slightly higher than Sn due to lanthanide contractions.