*$_Enriched uranium is one in which?

• A. Percentage of U‚Äö√á√á‚Äö√á√â‚Äö√á√ñ has been artificially increased
• B. Percentage of U has been artificially increased
• C. Percentage of U‚Äö√á√á‚Äö√á√â‚Äö√á√ë has been artificially increased
• D. Extra energy is pumped from outside