For a function of two variable, boundary value analysis yields.

Explanation

In standard boundary value analysis each variable is tested at five values — minimum, just above minimum, nominal, just below maximum and maximum — while all the other variables are held at their nominal value. That gives 4 boundary tests per variable plus a single all-nominal test that is shared by every variable, so the total is 4n + 1 test cases for n variables. For a function of two variables this works out to 4 × 2 + 1 = 9 test cases. Option (ii) is therefore correct; the 4n + 3 figure belongs to robust boundary value analysis in a different formulation and 2n + 4 has no basis.