option (D) is correct
average number of comparison(or searches) for successful search =(I(E)+n)/n where I(E) is the path length of all internal nodes(after considering external nodes in tree)and n is number of nodes
here given sorted elements of array so 1 element at level 1(root) then 2 elements at level 2 and 4 elements at level 3 and 3 elements at level 4
so number of comparison=(1*0+2*1+4*2+3*3+10)/10 =>2.9comparisons