Which of the following C-H bonds has the lowest bond dissociation energy?

The bond that gives the most stabilised radical on cleavage is the weakest. Diphenylmethane gives the diphenylmethyl radical, delocalised over two rings (BDE about 84 kcal/mol). 2-Methylpropane gives a tertiary radical (about 96), methane gives a methyl radical (about 105), and benzene gives a phenyl radical with the electron in a $\sigma$ orbital (about 112).