A mixture in which composition is constant throughout the mixture is said to be homogeneous mixture.
Now, oil and vinegar dressing is not considered as a homogeneous mixture because composition is not uniform.
Concrete is made up of three components. Thus, composition is not uniform, so it is not a homogeneous mixture.
A mixture of salt and pepper, when salt is mixed in pepper then the mixture is not uniform as white flecks of salt and black flecks of pepper can be seen in the mixture. Thus, it is not a homogeneous mixture.
Salt water is uniform mixture. Thus, it is a homogeneous mixture.
Thus, salt water is the correct answer.
