How is the critical radius of particles calculated?

• A. <a href="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3a.png"><img alt="The critical radius of particles calculated - option a" class="size-full wp-image-239234" height="41" src="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3a.png" width="28"/></a>
• B. <a href="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3b.png"><img alt="The critical radius of particles calculated - option b" class="size-full wp-image-239235" height="39" src="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3b.png" width="27"/></a>
• C. <a href="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3c.png"><img alt="The critical radius of particles calculated - option c" class="size-full wp-image-239236" height="36" src="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3c.png" width="23"/></a>
• D. <a href="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3d.png"><img alt="The critical radius of particles calculated - option d" class="size-full wp-image-239237" height="42" src="https://www.sanfoundry.com/wp-content/uploads/2018/05/engineering-materials-metallurgy-questions-answers-campus-interviews-q3d.png" width="25"/></a>