A firm has $43$ units of a certain product on hand. Forecasts for the first two planning periods are $20$ units each. A production quantity of $80$ units is planned to be available in period $3.$ Customer orders are $22$ for period $1$ and $17$ for period $2.$

What is the projected on hand inventory at the end of period $2?$

a$.$

$1$

b$.$

$12$

c$.$

$4$

d$.$

$20$

e$.$

$21$