Sumitomo Rubber Industries (SRI) is a Japan-based tyre manufacturer.

There are many factors that can influence the balance of power in a negotiation. These factors are classified into 3 levels:

Macro level: STEEPLE framework: social, technological, economic, environment, political, legal and ethical

Micro level: Porter's five forces:

Diagram Description automatically generated

One-to-one buyer-supplier dynamics.

The question asks about the micro factors that increases supplier's bargaining power. Among 5 answers, only 2 are likely to increase buyer's power:

There are no close substitutes for rubber: the buyer has to buy rubber, not any other material.

Costs of changing suppliers are high: buyer entails a large barrier if they want to switch supplier.

Other answers cannot be correct because:

SRI sets up its own rubber plantation: Buyer secures its own supply

SRI's purchase amount makes significant proportion of supplier revenue: Suppliers are reliant on buyer. If the buyer stops buying from them, they can face serious cash flow problems

Rubber from different suppliers is virtually similar: undifferentiated product would shift the power balance towards buyer.