The ordinary trading account is a locked storehouse of most valuable information to which cost system is the . . . . . . . .

The ordinary trading account is a record of all the transactions that a business makes in the course of its ordinary business activities. It includes sales, purchases, expenses, and income. This information is valuable because it can be used to track the profitability of the business, identify areas where costs can be reduced, and make informed decisions about future business activities.

A cost system is the key to unlocking this valuable information because it provides a framework for organizing and analyzing the data in the ordinary trading account. It allows businesses to identify the costs associated with each product or service, track the costs over time, and compare the costs of different products or services. This information can be used to make informed decisions about pricing, production, and marketing.

In conclusion, a cost system is the key to unlocking the valuable information contained in the ordinary trading account. It provides a framework for organizing and analyzing the data, which can be used to make informed decisions about pricing, production, and marketing.

The other options are incorrect because:

• Option B, “lock,” is incorrect because the ordinary trading account is not a locked storehouse. It is a record of all the transactions that a business makes in the course of its ordinary business activities.
• Option C, “house,” is incorrect because the ordinary trading account is not a house. It is a record of all the transactions that a business makes in the course of its ordinary business activities.
• Option D, “None of these,” is incorrect because the correct answer is A.