Usually, specific authorization is required for all of the following except

a. write-off of an uncollectible account receivable

b. sales on account which exceed the credit limit

c. a cash refund for goods returned without a receipt

d. sales of goods at the list price

D). Sale of goods at the list price.

Explanation:

Specific authorization is described as the process of equipping with the legal authority, access, or power to practice or operate a specific action or process to be carried out independently without any legal obstructions.

As per the question, specific authorization would be required for all of the given practices except for the 'sale of goods at list price' as it doesn't include special legal authority to be carried out. The other options (options A, B, and C) exemplify the practices like 'writing-off un-collectible account', 'a cash refund for goods returned without a spirit', and 'sales on account which has exceeded the credit limit' as these processes require certain power or privileges to receive access for these secured activities. Thus, option D is the correct answer.