Can I find zeros of a KKT (Kuhn Tucker condition) equation using "fmincon" for a constraint optimization complex number?

I am using fmincon to solve the optimization problem using the following command:

[res4,fval4]=fmincon(objective,x0,A,B,Aeq,beq,lb,ub,constfunc);
%Where @objective is the objective function
%and @constfunc is the nonlinear constrain

So far I know fmincon command is used to find local minimum of an objective function with constraint.

My questions are:

a. Can fmincon find the zeros of the objective function for some constraint? or it just deal with local minimizer.

b. Does the intitial value 'x0' has and impact of finding the finimizer even if the objective founction is bounded and continuous?

c. Can i calculate Lagrance multiplier from this command?

Thank you.