Sandra wants to evaluate 2 cot(-9pi/2). her work is shown below. what did she do wrong? 2 cot (-9pi/2) = 2 cot (9pi/2) 2 cot (-9pi/2) = 2 cot (pi/2) 2 cot (-9pi/2) = 2(0) 2 cot (-9pi/2) = 0 a)since cot is an odd function 2 cot (-9pi/2) does not equal 2 cot(9pi/2) b) since cot has a period of (pi) 2 cot(9pi/2) does not equal 2 cot (pi/2) c) since cot evaluated at pi/2 is not 0, 2 cot(pi/2) does not equal 2(0) d) since cot cannot be multiplied by a factor 2(0) does not equal 0