Step 1: Understand the role of resources in development.
Economic resources, including financial capital, infrastructure, and human resources, are fundamental to the development of any country. While physical resources are important, economic resources play a pivotal role in achieving sustainable development.
Step 2: Evaluate the options.
- Physical resources are important but are often ineffective without proper management and economic planning.
- Efficient management is essential but is dependent on the availability of economic resources.
- Economic resources are the most critical for economic growth and national development.
Step 3: Conclude.
The foremost need for the development of a country is economic resources, as they drive the economy and enable the proper utilization of physical and human resources.
Final Answer:
\[
\boxed{\text{Economic resources}}
\]