A company uses a forecasting model with both trend and seasonality to forecast the quarterly sales of one of its products The parameters for this seasonal forecasting model are a $=210$ b $=10\mathrm{.}4,$S$,=0\mathrm{.}945.$; S$\_\{2\}=0\mathrm{.}848$; S$\_\{3\}=1\mathrm{.}293$ and S$\_\{4\}=0\mathrm{.}914$ In which quarter of the year are the sales of this product usually the highest in relation to the trend line $?$