A company has had the following financial results for the last four years.

Year $1$ Year $2$ Year $3$ Year $4$

Sales $$1,250,000$ $$1,300,000$ $$1,359,000$ $$1,400,000$

Cost of goods sold $750,000785,000825,000850,000$

Gross profit $500,000515,000534,000550,000$

Inflation factor $1\mathrm{.}001\mathrm{.}031\mathrm{.}071\mathrm{.}10$

The company has analyzed these results using vertical common$-$size analysis to determine trends. The performance of the company can best be characterized by which one of the following statements?

Select one:

a$.$

The common$-$size trend in sales is increasing and is resulting in an increasing trend in the common$-$size gross profit margin.

b$.$

The common$-$size trend in cost of goods sold is decreasing which is resulting in an increasing trend in the common$-$size gross profit margin.

c$.$

The increased trend in the common$-$size gross profit percentage is the result of both the increasing trend in sales and the decreasing trend in cost of goods sold.

d$.$

The common$-$size gross profit percentage has decreased as a result of an increasing common$-$size trend in cost of goods sold.