For real roots of a quadratic equation, the discriminant must be:

1. greater than or equal to zero

2. greater than zero

3. less than or equal to zero

4. less than zero

If the Discriminant is greater than 0, then the roots are real and distinct.

If the Discriminant is equal to 0, then the roots are real and equal.

Thus, for real roots of a quadratic equation, the discriminant must be greater than or equal to zero.

Hence, option 1 is the correct option.