The correct answer is A. $1,500,000.
The flexible budget variable is the total amount of variable costs that a company expects to incur at a given level of production. It is calculated by multiplying the number of units produced by the per unit variable cost. In this case, the number of units produced is 3000 and the per unit variable cost is $500, so the flexible budget variable is $1,500,000.
Option B is incorrect because it is the total amount of fixed costs that a company expects to incur. Option C is incorrect because it is the total amount of variable costs that a company expects to incur at a higher level of production. Option D is incorrect because it is the total amount of costs that a company expects to incur at a higher level of production.