May I ask for a solution and explanation to the question for a better understanding. Thank you!

Pierce Corporation has the following gross profits for 2018 and 2019: Sales = 2019 - P810,000; 2018 - P792,000. Cost of sales = 2019 - 480,000; 2018 - 464,000. Gross profit = 2019 - P330,000; 2018 - P328,000. Sales price was 10% lower during 2019.

The owners would like to know what reasons caused the current performance of the company and ask your opinion. Through review of the complete records you were able to obtain this additional information: (1) The selling price for every unit is P7.20 during 2018 and; (2) The marketing department did a tremendous job and was able to increase sales units by 20% during 2019. The percentage increase (decrease) in unit cost is:

a. 20%

b. (20%)

c. 44%

d. (44%)