Consider the following recursive algorithm:

Algorithm Q$($n$)$

$//$Input: A positive integer $n$

if $n=1$ return $1$

else return $Q(n-1)+2**n-1$

a$.$ What is the in$|$

b$.$ What is its basic operation?

c$.$ How many times is the basic operation executed? choose your answer...

d$.$ What is the efficiency class of this algorithm?