_ A fission chain reaction in uranium can be developed$?

• A. By increasing the contents of U‚Äö√á√á‚Äö√á√â‚Äö√á√ñ
• B. By slowing down fast neutrons so that U‚Äö√á√á‚Äö√á√â‚Äö√á√ñ fission continues by slow neutron
• C. Both (A) and (B)
• D. None of these