You should investigate automatically low tenders by clarifying the bid with the supplier. It could be they have misunderstood the requirement. Or the bid could be genuine and they can really provide best value for money.
But without enquiring, you just don't know.

The EXW (Ex Works) term means the seller's responsibility ends once goods are made available at their premises. The buyer must take on costs and risks from that point, including loading, transport, and export clearance. Because the seller is not responsible for logistics, the quoted price is lower. In contrast, FCA includes delivery to a carrier, FOB covers loading onto a vessel, and CIP includes carriage and insurance arranged by the seller. By accepting these responsibilities, the buyer leveraged cost savings, demonstrating knowledge of Incoterms and alignment with efficient sourcing practices.
Reference: CIPS L4M4 Study Guide (v2), LO: "Application" - Incoterms responsibilities and cost-sharing.

During tender evaluation, buyers must ensure that each submission is analysed thoroughly and consistently.
Producing a report on each submission (1) supports transparency, auditability, and fairness. Checking arithmetical accuracy (3) ensures that pricing data is correct and prevents calculation errors from misleading the evaluation. Reviewing pre-qualification questionnaires is part of the earlier stage, not tender analysis, while market dynamics are external context, not part of evaluating responses. Responsible sourcing highlights the importance of structured and auditable evaluation processes to protect against bias, ensure compliance, and provide stakeholders with a defendable record of decisions.
Reference: CIPS L4M4 Study Guide (v2), LO: "Implementation" - tender evaluation and analysis procedures.

International trade relies on proper documentation. A certificate of origin (2) confirms where goods are produced, often required for customs clearance and to determine tariffs. A purchase order (3) provides formal buyer intent and agreement of terms, forming the basis for customs and logistics processes. Product quality statistics (1) and supplier financial position (4) are relevant for supplier selection and monitoring but not directly for import/export processes. Responsible sourcing requires procurement professionals to ensure correct documentation is used to avoid delays, penalties, or breaches of trade regulations.
Reference: CIPS L4M4 Study Guide (v2), LO: "Application" - documentation in international sourcing.

Carry out due diligence is the correct answer. The other answers are incorrect:
- ensure all 46 suppliers publish an Anti Slavery Statement in line with the Modern Slavery Act is wrong because thequestionstates that some suppliers are international. The legislation is UK, meaning international suppliers don't have to do the statement. It also only applies to companies with a turnover of £36m, and some of Zeb's suppliers may be smaller than this.
- work with less suppliers to reduce the risk of slavery entering the supply chain is a silly answer be-cause Zeb probably needs all of his suppliers. There's probably a reason he uses that many.
- ask all suppliers to get Fair Trade accredited is also a silly answer. Fair Trade only exists in some industries such as cocoa and bananas. Zig Zag Zips is in manufacturing so it's probably not going to be able to fairtrade accredit some of the stuff it buys.