The correct answer is: B. Decrease gross profit as well as net profit.

If the opening inventory of a business is undercast, it will result in an increase in cost of goods sold, which will in turn decrease gross profit. Gross profit is calculated by subtracting cost of goods sold from sales revenue. Net profit is calculated by subtracting cost of goods sold, operating expenses, and taxes from sales revenue. Therefore, if cost of goods sold is increased, net profit will also decrease.

Here is a more detailed explanation of each option:

  • Option A: Increase gross profit and decrease net profit. This is incorrect because, as explained above, undercasting the opening inventory will decrease gross profit.
  • Option B: Decrease gross profit as well as net profit. This is the correct answer because, as explained above, undercasting the opening inventory will decrease gross profit and net profit.
  • Option C: Increase value of assets. This is incorrect because undercasting the opening inventory will not affect the value of assets. The value of assets is determined by the cost of the assets, not by the amount of inventory that is on hand.
  • Option D: Increase gross profit as well as net profit. This is incorrect because, as explained above, undercasting the opening inventory will decrease gross profit.