We are evaluating whether or not to invest in a company. Indicate whether each of the following separate trends would make us more or less likely to invest.

a$.$ Return on equity is increasing, from $17\%$ to $21\%.$

b$.$ Days' sales in inventory is increasing, from $25$ days to $42$ days.

c$.$ Profit margin is decreasing, from $22\%$ to $16\%.$

d$.$ Return on total assets is increasing, from $11\%$ to $15\%.$