Identify whether each of the following items constitute positive or negative evidence when a taxpayer assesses whether a valuation allowance is required or should be adjusted.
a. Product orders are increasing.
b. Only two years remain for the taxpayer's net operating loss carry forward.
c. Book income for the past three years totals to a negative amount.
d. Investment assets held by the taxpayer show a realized gain.
e. The industry in which the taxpayer operates is in a down cycle.
f. The entity's tax plan includes a switch from MACRS accelerated depreciation to straight-line?