Question

closing stock is valued at lower of cost or market price.which concept of accounting is applied here.

Answer 1

Prudence Concept demands. That

Answer 2

Closing stock is value at lower cost or market price.

The concept of accounting applies her is prudence concept.

Prudence concept is an accounting principle in which the revenue is required only when assured but expenses are recorded  as soon as possible.

This is used in the above case.