What is the direct manufacturing labour partial productivity, assuming $20,000$ units were produced during the year and $80,000$ direct manufacturing labour$-$hours were used?

Question $8$ options:

$4\mathrm{.}00$ unit per direct manufacturing labour$-$hour

$0\mathrm{.}75$ unit per direct manufacturing labour$-$hour

$0\mathrm{.}50$ unit per direct manufacturing labour$-$hour

$0\mathrm{.}25$ unit per direct manufacturing labour$-$hour