How to combine two IEnumerable list?

Question

 

I have two list :

public IEnumerable<int> A{ get; set; } 

public IEnumerable<int> B{ get; set; }  

 

 i want C to be a combination of both A and B.

  public IEnumerable<int> C{ get; set; }

 

 

how can this be done? thank you in advance :)