Which situation would most likely be flagged as material?

A customer of our client whose cumulative balance totals $75,000 of accounts receivable of $600,000 (but no one sales invoice totals more than $8,500)

A customer of our client who has only one receivable of $25,000 of an accounts receivable balance of $1 million

A customer of our client who has two sales invoices of $20,000 each with a total client receivable balance of $800,000