Costing system, which omits some of journal entries in accounting system is known as

in-time costing
trigger costing
back flush costing
lead time costing

The correct answer is C. back flush costing.

Backflush costing is a costing system that omits some of the journal entries in the accounting system. It is a just-in-time costing system that is used to track costs in a manufacturing environment. Under backflush costing, costs are not recorded when materials are purchased or when labor is incurred. Instead, costs are recorded when finished goods are sold. This can help to reduce the amount of time and effort that is required to track costs.

A. In-time costing is a costing system that tracks costs as they are incurred. This can help to provide more accurate information about the costs of products or services. However, in-time costing can be more time-consuming and expensive than other costing systems.

B. Trigger costing is a costing system that is used to track costs when certain events occur. For example, trigger costing might be used to track the costs of a product when it is shipped to a customer. Trigger costing can be helpful in identifying the costs of specific activities or products.

D. Lead time costing is a costing system that is used to track costs from the time that a product is ordered to the time that it is delivered. Lead time costing can be helpful in identifying the costs of the production process.