What is missing in this logic of finding a path in the tree for a given sum (i.e checking whether there will be a path from roots to leaf nodes with given sum)?

checkSum(struct bin-treenode *root , int sum) :
  if(root==null)
    return sum as 0
  else :
     leftover_sum=sum-root_node-->value
     //missing

A. code for having recursive calls to either only left tree or right trees or to both subtrees depending on their existence

B. code for having recursive calls to either only left tree or right trees

C. code for having recursive calls to either only left tree

D. code for having recursive calls to either only right trees

Answer: Option A