A country can produce more units of good B without reducing the units
of good A it produces. would be UNDERUTILIZATION.
This indicates that the country is not using the full potential of their resources
A country cannot produce more units of good A without producing fewer units
of good B : would be EFFICIENCY
This means that the country has allocated all of their resources and labor properly to the point where there is no wiggle room
A country wants to produce 10 units of good A and 12 units of good B but
can produce only 5 units of good A and 4 units of good B.: UNATTAINIBILITY
This means that the country has a certain target in mind, but along the way they failed to reach the target