What is the purpose of the pos parameter in this recursive function?
def reverse_str(st, pos):
""" Returns a new string that is the reverse of st When first called, the pos parameter must be zero """
if pos == len(st):
return ""
return reverse_str(st, pos+1) + st[pos]
a. To keep track of what subproblem the function is currently working on.
b. To handle exceptions.
c. Recursive functions require an even number of parameters.
d. Pos is the string which will be reversed.