A continuous documentary chain from lawful origin to the business account: sale agreements, tax records, statements covering every intermediate account and each transfer between them.
Trace the path, not just the balance
The requirement is that the capital be the investor's own and lawfully obtained, and the evidence has to survive being followed backwards. A single statement showing the funds arriving proves nothing about where they came from. Where the money originated in the sale of Canadian assets, the sale agreement, the closing statement and the tax treatment of the proceeds all belong in the file.
Where it accumulated from farm or business income over years, tax filings and financial statements are the natural evidence. Every account the money passed through needs coverage for the relevant period, including accounts used only briefly. Gaps happen with closed accounts and dissolved institutions; identify them plainly and provide what secondary evidence exists rather than leaving a silent break in the chain.