If '+' means '-', '-' means `'xx','xx'` means `'-:'` and `'-:'` means '+' which combination will give you the value of '0' in `42**4**12**20**9?`

Options

A. `- -: xx +`
B. `-: + - xx`
C. `+ - -: xx`
D. none of these

Explanation

Option (1) `42**4**12**20**9`
`rArr 42-4-:12xx20+9`
After changing the signs
`42xx4+12-:20-9`
`rArr 42xx4+(12)/(20)-9`
`rArr 168+(3)/(5)-9 ne 0`
Option (2)
`42**4**12**20**9`
`rArr 42-:+12-20xx9`
After changing the signs
`42+4+12-20xx9`
`42+4-12xx20-:9`
`rArr 42+4-(12xx20)/(9)`
`rArr 42+2-(80)/(3)`
`rArr 46-(80)/(3) ne 0`
Option (3)
`42**4**12**20**9`
`rArr 42+4-12+20xx9`
After changing the signs
`rArr 42-48+(20)/(9) ne 0`
Option (4) `42**4**12**20**9`
`42xx4-12-:20+9`
After changing the signs
`42-:4xx12+20-9`
`rArr (21)/(2)xx12+20-9`
`rArr 21xx6+20-9 ne 0`