how to combine to matrix with the same rows and different columns

I have matrix A with n rows and three columns, matrix B with n rows and one column. For instance, matrix A and B could be as follows:

 A= [1 4
 3 6
 4 7
 1 3
 5 2
 7 9]

 B=[1
 2
 2
 3
 2
 5]

As you see, matrix A and B have the same number of rows. I would like to produce matrix C from matrix A, but only rows which are “2” in matrix B.

 C=[3 6
 4 7
 5 2]

It would be appreciated if you could give me some ideas for solving this problem.

Thanks

Answer 1

[Walter Roberson]

 A= [1 4
 3 6
 4 7
 1 3
 5 2
 7 9];
 C = A(B == 2, :);

[Maryam Hamrahi]

Thank you very much Walter Roberson.

your help is really appreciated.