Irrational numbers are numbers that cannot be expressed or represented as a ratio of two integers. Thus, the answer is K. Infinite many because there are infinite numbers that can be found between numbers 1 to 6; numbers that cannot be expressed as repeating decimals or so.
Think that between numbers 1 to 2 , there are many irrational numbers between same in numbers 2 to 3 , 3 to 4, 4 to 5 and 5 to 6.
Thus, There are infinite numbers of irrational number between numbers 1 to 6