At December 31, 2007 and 2008, our financial instruments included cash and cash equivalents, trade receivables, marketable securities and accounts payable. Our subordinated notes outstanding at December 31, 2007, were repaid in December 2008. The carrying amount of cash and cash equivalents, trade receivables, and accounts payable approximates fair value due to the short-term maturities of these instruments. The estimated fair values of financial assets were determined based on quoted market prices at year-end. The estimated fair value of the subordinated notes payable was determined based on the present value of its future cash flows using a discount rate that approximates our current borrowing rate.

Required
a. The carrying amount of cash and cash equivalents, trade receivables and accounts payable approximates fair value. Why?
b. December 31, 2007
1. Why are investments in marketable equity securities of GSSL classified as fair value measurements under Level 1?
c. December 31, 2007 and December 31, 2008
i. Why are marketable equity securities held in supplemental retirement plans partially classified under Level 1 and partially under Level 3?
ii. Why are marketable equity securities held in life insurance contracts classified under Level 1?
d. During 2008, an impairment charge of $253,000 was made related to developed technologies. Why?