Consider the following recursive C function that takes two arguments.unsigned int foo(unsigned int n, unsigned int r) { if (n>0) return ((n%r) + foo(n/r, r)); else return 0; }What is the return value of the function foo when it is called as foo(345, 10)?

The recursive function foo(n, r) computes the sum of the digits of n in base r.

Tracing the execution for foo(345, 10):

• foo(345, 10) returns (345 % 10) + foo(34, 10) = 5 + foo(34, 10)

• foo(34, 10) returns (34 % 10) + foo(3, 10) = 4 + foo(3, 10)

• foo(3, 10) returns (3 % 10) + foo(0, 10) = 3 + foo(0, 10)

• foo(0, 10) hits the base case (n <= 0) and returns 0

Summing the values:

Therefore, the return value is 12, which corresponds to option (B).