A deductible temporary difference arises when the carrying amount of an asset or the carrying amount of a liability is less than its tax base, which would result in a future tax deduction. Let's analyze each option:

A. An automobile with accelerated depreciation for tax purposes but not for accounting, leading to a carrying value of 2,100 and a tax base of 1,500, represents a deductible temporary difference. The difference between the book value (2,100) and the tax base (1,500) creates a future tax deduction, as the tax base is lower than the carrying amount in the financial statements.

B. The interest receivables recorded in the accounting books for 300 does not represent a deductible temporary difference, as it relates to the recognition of revenue, not a difference between the tax base and carrying amount.

C. Accrued expenses with a carrying value of 2,400 that will be deductible for tax purposes on a cash basis also does not represent a deductible temporary difference, as it pertains to the timing of the tax deduction, not the difference in the amounts.

Therefore, the correct answer representing a deductible temporary difference is: A. An automobile has accelerated depreciation for tax but not for accounting purposes, resulting in carrying value of 2,100 and tax base of 1,500.