4.9 Barriers to Economic Growth and Economic Development

A supply-side barrier constrains an economy's productive potential — the maximum output it can generate from available resources. Poor infrastructure raises the cost of producing and distributing goods, directly limiting how much the economy can supply.

When roads are impassable for months, farmers face higher transport costs, spoilage of perishable produce, and severely restricted access to larger, higher-priced city markets. These costs reduce the profitability of expanding production.

Lower profitability discourages output expansion and deters domestic and foreign investors from locating operations in the region. Aggregated across many producers, this suppresses the region's contribution to GDP — a classic supply-side constraint on growth.

The correct answer identifies the mechanism: limited market access and higher transport costs reduce output, income, and investment incentives — all supply-side channels through which poor infrastructure constrains economic growth.

The question asks which option correctly identifies how an impassable seasonal road acts as a supply-side barrier to growth — the focus is on production constraints, not demand or government spending.

Option A focuses on consumer demand in the city market. This is a demand-side framing. The question specifically asks about a supply-side barrier — the limitation is on the ability of producers to supply goods, not on urban consumers' willingness to buy.

Option C claims the road creates excess supply in the city by preventing exports abroad. This is internally contradictory — if the road is impassable, goods cannot reach the city at all, let alone create excess supply there.

Option D refers to government road maintenance costs reducing tariff revenue. This is economically implausible and conflates infrastructure maintenance costs with trade policy in an irrelevant way.

Option B correctly identifies the supply-side mechanism: poor road infrastructure limits market access, raises transport costs, reduces output and producer income, and discourages further investment — all of which constrain productive capacity and economic growth.