Explain the answer and show all workings. Please note that D is not the correct answer.

Silco Pty Ltd manufactures various lines of computer equipment. They are planning to introduce a line of laptop computers in January 2008. Current plans call for the production and sale of 1000 computers with estimated production costs as follows. Variable costs: $450 000 Manufacturing $100 000 Selling and administrative $550 000 Total variable costs Fixed costs: $300 000 Manufacturing $180 000 Selling and administrative $480 000 Total fixed costs $1 030 000 Total costs