Book-keeping is an essential process of accounting that involves recording all financial transactions of a business. The main objectives of book-keeping are:

1. Complete Recording of Transactions:
Book-keeping involves the systematic recording of all financial transactions of a business. This includes sales, purchases, expenses, receipts, and payments. The main objective of book-keeping is to ensure that all transactions are recorded accurately and completely in the books of accounts.

2. Ascertainment of Financial Effect on the Business:
Book-keeping helps in determining the financial effect of each transaction on the business. This involves the classification and summarization of transactions into various categories such as assets, liabilities, equity, income, and expenses. The main objective of book-keeping is to provide accurate and reliable financial information that can be used for decision-making.

3. Analysis and Interpretation of Data:
Book-keeping also involves the analysis and interpretation of financial data. This helps in identifying the financial strengths and weaknesses of the business, as well as any trends or patterns that may be emerging. The main objective of book-keeping is to provide meaningful insights into the financial performance of the business.

4. (a) and (b) both:
The correct answer is option 'D' which means that book-keeping has two main objectives, which are the complete recording of transactions and the ascertainment of the financial effect on the business. Both objectives are equally important and are interconnected. Accurate and complete recording of transactions is necessary to ascertain the financial effect on the business, which in turn helps in the analysis and interpretation of financial data.