What is a ledger?
a. a company's main book for recording transactions
b. a company's record of liquid assets
c. a company's system of providing invoices to customers
d. a company's record of insured assets

(A) A company's main book for recording transactions

Explanation:

 A ledger is the organization principle book in the company for recording all the economical transactions. The ledger is also known as the computer file and it is basically measured in the monetary unit in the form of account type which  contain all the credits and also the debits balance.

A ledger is the type of computer file which is present permanently in the form of summary of all the transaction. Therefore, Option (A) is correct.