Answer:
[tex]A\subset B[/tex]
Step-by-step explanation:
Let A and B, be two non-empty sets, then set A is a subset of set B if all elements in set A can be found in set B.
The given sets are:
A={1,2} and B={1,2,3,4}
We can observe that, all the elements in set A are also in set B.
This means that set A is a subset of B.
We write this as:
[tex]A\subset B[/tex]
The correct answer is option D.
