[tex] \sqrt{ - 180 {x}^{16} } \\ = \sqrt{( - 1) \times \: 2 \times 2 \times 3 \times 3 \times 5 \times {x}^{8} \times {x}^{8} } \\ = (2 \times 3 \times {x}^{8} ) \sqrt{( - 1) \times 5 } \\ = 6 {x}^{8} \times \sqrt{ - 1} \times \sqrt{5} \\ = 6 {x}^{8} i \: \sqrt{5} [/tex]
so answer is option 4
