If a $25\%$ increase in all inputs increases a firm$$s output by $15\%,$ then its long run average cost curve, LRAC, is $\_\_\_\_\_$ because the firm is experiencing $\_\_\_\_\_.$

Group of answer choices

upward sloping; decreasing returns to scale $($DRTS$).$

upward sloping; increasing returns to scale $($IRTS$).$

horizontal; constant returns to scale $($CRTS$).$

downward sloping; increasing returns to scale $($IRTS$).$

downward sloping; decreasing returns to scale $($DRTS$).$

vertical; constant returns to scale $($CRTS$).$