Addition: The addition of two integers produces another integer.
Subtraction: The subtraction of two integers produces another integer.
Multiplication: The product of two integers is an integer.
Division between two integers can produce a rational number that is not in the set of integers e.g. 1/3
This only includes the four basic arithmetic operations, you can include exponentiation and the modulo operation if you want to for the same reasons as above.
I think it’s the first one because you mirror ABC from the m-axis and then rotate ABC 90 degrees clockwise from point B’ to get to the position of triangle A”B’C”