The scenario describes a Procure-to-Pay style cycle: raising purchase orders, processing payments, capturing transactions, and reconciling — this spans Purchasing (raises POs), Inventory (receipts/stock tied to POs), Cash Management (payment processing/reconciliation of bank statements), and GL (final posting/reconciliation of all transactions). Istore is Oracle's e-commerce/shopping-cart storefront module (Order-to-Cash, customer-facing), and Order Management handles sales order processing (also Order-to-Cash) — neither fits a purchasing/payment/reconciliation flow, which is why they're excluded. The four correct modules together form the standard back-office procurement financial trail.