单选题 An analystdoes research about cash flow from operating and gathers the following information about a company:

	2011	2010
Depreciation expense	$5000	$4000
Gain on sales of equipment	$900	$0
tax	$1987	$1235
Working capital	$40000	$45000

Under U. S. GAAP, the adjustment to net income to arrive at 2011 cash flow from operating activities is:
A. subtracting $900.
B. adding $9100.
C. subtracting $9100.