Given empty Queue customerNums, what are the queue's elements after the following code block is executed?

customerNums.add$(5)$;

customerNums.add$(2)$;

customerNums.add$(6)$;

customerNums.remove$()$;

customerNums.remove$()$;

Question $18$ options:

$[5]$

$[6]$

$[2,6]$

$[5,2]$