Companies typically use the Straight$-$Line method for financial reporting purposes and an Accelerated Depreciation method for tax returns because

a$.$ Accelerated Depreciation allows for higher depreciation expense on the tax return and therefore reduces taxable income creating tax savings for the current year

b$.$ Accelerated Depreciation is not allowed in accordance with GAAP

c$.$ Straight$-$Line depreciation is calculated using the useful life of the asset and therefore most accurately captures the depletion of the asset over the course of times and appropriately $$expenses$$ that depletion in the P&L

d$.$ A$,$B&C