The half$-$year convention generally applies to $...$

a$.$ all assets being deprecinted under MACRS.

b$.$ assets other than buildings being depreciated under MACRS.

c$.$ assets other than passenger autos being depreciated under MACRS.

d$.$ assets other than buildings and passenger autos being depreciated under MACRS.

The mid$-$month convention applies to $...$

a$.$ assets purchased during the last $3$ months whose aggregate basis exceeds $40\%$ of the aggregate basis of assets purchased during the year.

b$.$ assets other than buildings purchased during the last $3$ months whose aggregate basis exceeds $40\%$ of the aggregate basis of assets other than buildings purchased during the year.

c$.$ buildings.

d$.$ buildings and land.

In units of production depreciation, the depreciation rate is calculated as$...$

a$.($acquisition cost $-$ residual value$)/$total estimated units of production.

b$.($historical cost $-$ salvage value$)/$total estimated units produced, labor hours used or miles driven.

c$.($depreciable base$)/$total estimated units of output.

d$.$ any of the above.