E.L. Ullman identified certain basic factors affecting interaction between regions. Consider the following statements:

A. There must be a demand in one region that can be met from another region.
B. The area of demand must be able to pay for the supply so that a two-way movement develops.
C. The movements will only take place if each region is self-sufficient.
D. Interaction between the regions will only take place if there are no intervening opportunities.
E. Interaction between the regions will only take place if the product can be moved.

Choose the correct answer from the options given below:

Correct option is D

E.L. Ullman (1956) proposed that spatial interaction between regions is based on three major principles:

Complementarity – There must be a demand in one region and supply in another (A).
Transferability – The product must be able to move from one place to another (E).
 Intervening Opportunity – If there is a closer source, interaction will be less likely (D).

Thus, the correct conditions for regional interaction include:
Demand and supply relationship (A & B).
The ability to move goods (E).
Lack of intervening opportunities (D).

Thus, the correct answer is:
 A, B, D & E

Information Booster: 

1. Complementarity (A & B)

• One region must have a surplus, and another must have a demand.
• Example: India exports IT services to the USA due to demand.

2. Transferability (E)

• The product must be movable at an economically feasible cost.
• Example: Shipping crude oil is easier than moving fresh food over long distances.

3. Intervening Opportunity (D)

• If a closer alternative exists, interaction between two regions decreases.
• Example: If Nepal imports rice from India, it won’t import from Thailand due to distance.

Additional Knowledge:

C. The movements will only take place if each region is self-sufficient.

• Incorrect because Ullman’s model states that regions interact due to differences, not self-sufficiency.
• If a region is self-sufficient, there is no need for interaction.