None of the given option is correct. When the bubble gets detached,
Buoyant force = force due to surface tension
Force due to excess pressure = upthrust
Access pressure in air bubble `=(2T)/(R)`
`(2T)/(R)(pir^2)=(4piR^3)/(3T)rho_wg`
`impliesr^2=(2R^4rho_wg)/(3T)`
`implies r=R^2sqrt((2rho_wg)/(3T))`