33. Consider the following statements regarding the number of sign change in the first column of Routh in respect of the characteristic equation s 2 þ 2as þ 4: 1. If a ¼ þ”, where ” is near to zero, number of sign changes will be equal to zero. 2. If a ¼ 0, the number of sign change will be equal to one. 3. If a ¼ “; where ” ¼ near zero, the number of sign changes will be equal to two. Of these statements: (a) 1, 2 and 3 are correct (b) 1 and 2 are correct (c) 2 and 3 are correct (d) 1 and 3 are correct