Multiple choice technology programming languages Which of the following variable declarations are valid. a.y2 b._x c.7x d.this_is_test a b c d Reveal answer Fill a bubble to check yourself A,B,D Correct answer Explanation Ruby variables can start with letters or underscores, but not digits. y2 is valid (starts with letter), _x is valid (starts with underscore), this_is_test is valid. 7x is invalid because it starts with a digit.