With a continuous paper trail: grain and machinery sale invoices, settlement statements, deposits into an identified account, and the transfers out to the seller or the business.
Every dollar needs a beginning, a path and an end
Hypothetical example: A reviewer is not testing whether the investor is wealthy but whether the specific money used was lawfully obtained and can be followed. For an agricultural contractor the sources are usually identifiable: grain elevator settlement statements, invoices for machinery sold at auction with the auctioneer's remittance, proceeds of a land severance, or a loan advance. Each needs its own chain.
Show the sale document, the deposit into a named account on a named date, any movement between accounts, the currency conversion, and the outgoing transfer. Gaps are what cause requests for further evidence, and the most common gap is a large cash deposit with no supporting sale document. Where funds are borrowed, provide the loan agreement and show what secures it, because a loan secured by the assets of the American business itself does not represent the investor's capital at risk.
Keep the whole chain in one indexed bundle rather than in email attachments.