Correct Answer - B
`T=(2m_(1)m_(2))/(m_(1)+m_(2))g=(2xx1xx2)/(1+2)xx10N=40/3N`
If `r` is the minimum radius, then
Breaking stress `=(40/3)/(pir^(2))` or `40/(3pi)xx10^(6)=40/(3pir^(2))`
or `r^(2)=1/(10^(6))` or `r=1/(10^(3))m`
or `r=1/(10^(3))xx10^(3)m=1mm`