Here we can write √(-25) as product of √(-1) and √25
√(-1) = i (iota)
√25 = 5
√(-25) =5i.............(1)
√(-64) = √(-1) * √64
√(-1) =i and √64 =8
√(-64) = 8i...............(2)
multiplying (1) and (2)
5i * 8i = 40 i²
i²=-1
so 40i² =-40
Answer is option B. -40
