Which Transact-SQL batch should you use?

You administer a Microsoft SQL Server 2012 database that contains a table named
AccountTransaction.
You discover that query performance on the table is poor due to fragmentation on the
IDX_AccountTransaction_AccountCode non-clustered index.
You need to defragment the index. You also need to ensure that user queries are able to use the
index during the defragmenting process.
Which Transact-SQL batch should you use?

A.
ALTER INDEX IDX_AccountTransaction_AccountCode ON AccountTransaction.AccountCode
REORGANIZE

B.
ALTER INDEX ALL ON AccountTransaction REBUILD

C.
ALTER INDEX IDX_AccountTransaction_AccountCode ON AccountTransaction.AccountCode
REBUILD

D.
CREATE INDEX IDXAccountTransactionAccountCode ON AccountTransaction.AccountCode WITH
DROP EXISTING