Concept:The ledger is the principal book where accounts are classified and summarized.
Explanation:A ledger is a permanent book of account.
Each transaction, first recorded in the journal, is classified under a specific account head in the ledger.
All related transactions are grouped and summarized to give the final position of each account.
Option B is correct because the ledger contains the classified and summarized record of all accounts.
Option A is wrong because a balance sheet is a financial statement, not a book of account.
Option C is wrong because a trial balance is only a summary of ledger balances.
Option D is wrong because a journal is the book of original entry, not the book of classification.
Answer:B. ledger