Which of the following accounting policies is an example of costs versus benefits constraint being exercised in the disclosure of financiaL information.

A$)$ inventory is valued at lower of cost or market.

b$)$ property, plant and equipment are appraised and revalued every three years.

c$)$ biological assets are stated at fair value unless the fair value cannot be measured reliably.

d$)$ Research and development costs are expensed as incurred.