What is true about indexes?

• A. Indexes enhance the performance even if the table is updated frequently
• B. It makes harder for sql server engines to work to work on index which have large keys
• C. It doesn‚Äö√Ñ√∂‚àö√ë‚àö¬•t make harder for sql server engines to work to work on index which have large keys
• D. None of the mentioned