Which of the following statements is/are correct?

(a) is correct. As we move down the group the size of the atom increases and hence internuclear distance increase and bond energy decreases from C to Sn                                            C                     Si                         Ge                          SnM-M                                348                 297                       260                        240Bond Energy(kJ/mole)b) is correct. As the size of the atom increases attractive forces between the atoms decrease and hence boiling point decreases from Si to Pb.                                            Si                     Ge                         Sn                      PbBoiling point(°C )          3280                2850                     2623                 1751c) is correct. Carbon being smallest in size is most electronegative in its family                                             C                   Si                      Ge                Sn        PbElectronegativity order 2.5                   1.8                   1.8               1.8       1.8(Pauling scale)d) is correct due to improper screeing of s and p-electrons by the inner d electrons in Ge so the sum of 3rd  and 4th  I. E. of Ge>Si .