Read the following passage and mark the letter A, B, C or D to indicate the correct word or phrase that best fits each of the numbered blanks

Rapid urbanization can hold long-term economic, social and environmental promise for developing countries (23) ____ investments made now in infrastructure, housing and public services are efficient and sustainable, the World Bank says in a new report.

In the next two decades, cities are (24) ____ to expand by another two billion residents, as people move in unprecedented numbers from rural areas to pursue hopes and aspirations in cities. More than 90% of this urban population growth is expected to occur in the developing world, (25) ____ many cities are already struggling to provide basic needs such as water, electricity, transport, health services and education.

Report authors note that most new urban growth will not take (26) ____ in the “megacities” of the world e.g. Rio de Janeiro, Jakarta or New Delhi but rather in less commonly recognized “secondary” cities - places like Fushun in China, and Surat in India.

To help policymakers prepare for and manage growth, the report distills lessons learned from 12 countries across all geographic regions and stages of urbanization. It then translates these global lessons (27) ____ practical policy advice.

(23) ..............

• A. 
  if
• B. 
  unless
• C. 
  whether
• D. 
  while