Help with these radical/square root questions

We know that i² = -1
[tex]\heartsuit[/tex] [tex]\sqrt{-28} = \sqrt{i^2\times7\times2^2} = 2i\sqrt{7}[/tex]
[tex]\heartsuit[/tex] [tex]\sqrt{-63} = \sqrt{i^2\times7\times3^2} = 3i\sqrt{7}[/tex]
[tex]Given\;that\;\sqrt{-28}\;is\;subtracted\;from\;\sqrt{-63}[/tex]
[tex]\implies \sqrt{-63} - \sqrt{-28} = 3i\sqrt{7} - 2i\sqrt{7} = i\sqrt{7}[/tex]
Option (2) is the Answer