Underallocated$/$undercosted overhead occurs when

A$.$ allocated overhead all year long is greater than the actual manacturing overhead at year end

B$.$ estimated overhead at the beginning of the year is less than the actual manacturing overhead at year end

C$.$ estimated overhead at the beginning of the year is greater than the actual manacturing overhead at year end

D$.$ allocated overhead all year long is less than the actual manacturing overhead at year end