Let's classify each item as an "Addition" or a "Subtraction" in the Schedule M$1$ reconciliation:

a$.$ Life insurance proceeds received upon death of covered executive.

Subtraction: These proceeds are generally not taxable and are included in book income, so they are subtracted to reconcile to taxable income.

b$.$ Tax depreciation in excess of book depreciation.

Subtraction: Tax depreciation is often higher than book depreciation due to accelerated methods allowed for tax purposes, so the excess is subtracted to reconcile to taxable income.

c$.$ Federal income tax per books.

Addition: Federal income taxes are not deductible for tax purposes, so they are added back to reconcile to taxable income.

d$.$ Capital loss in excess of capital gain.

Addition: Capital losses in excess of capital gains are not deductible for tax purposes, so they are added back to reconcile to taxable income.

e$.$ Charitable contributions in excess of taxable income limitation$.$

Addition: Contributions exceeding the deductible limit are not deductible for tax purposes, so they are added back to reconcile to taxable income.

f$.$ Premiums paid on life insurance policies covering executives $($corporation is beneficiary$).$

Addition: These premiums are not deductible for tax purposes, so they are added back to reconcile to taxable income.

Correct classifications:

a$.$ Subtraction

b$.$ Subtraction

c$.$ Addition

d$.$ Addition

e$.$ Addition

f$.$ Addition