Which country became the first in the world to use drones as part of its regular national mail delivery service?

Introduction / Context:
This question focuses on technological innovation in postal services. Around the world, national postal agencies have experimented with drones to deliver mail and parcels, especially in hard to reach areas. The first country to incorporate drones into a regular national mail service became a notable current affairs fact, often tested in examinations.

Given Data / Assumptions:
- The question asks which country first used drones for national mail service on a regular basis.
- Options are Russia, France, Sweden, China and United States of America.
- We assume the reference is to official, scheduled drone mail routes, not one time demonstrations by private companies.

Concept / Approach:
France became the first country where the national postal service started a regular drone delivery route for mail, particularly to serve remote or mountainous regions. The French postal service introduced a drone that carried parcels along a fixed route, making France the first country to integrate such service into its national postal system rather than just a pilot by a private firm.

Step-by-Step Solution:
Step 1: Recall news reports about a European country pioneering regular drone deliveries for its national postal service. Step 2: Remember that this initiative was associated with La Poste, the French postal service. Step 3: Match this with the list of countries and identify France. Step 4: Conclude that France is the correct answer.

Verification / Alternative check:
An alternative check is to consider what other countries are known for drone delivery experiments. The United States and China have many private companies testing drones, but these are commercial pilots rather than national mail services. Russia and Sweden have also experimented, but the specific milestone of first national postal drone route belongs to France. This supports choosing France.

Why Other Options Are Wrong:
Russia is wrong because, although it has tested drones, it was not the first to use them in a regular national mail service context.
Sweden is incorrect; it has been innovative in technology but does not hold this specific first position in postal drone use.
China is wrong here because its drone deliveries are largely associated with private e commerce companies rather than the first national postal service route.
United States of America is also incorrect; most high profile drone projects there have come from private companies, and it was not the first national postal service to establish a scheduled drone route.

Common Pitfalls:
Candidates often assume that the first technological innovation must come from the United States or China due to their strong tech industries. Others may guess randomly among European countries. Remembering the specific news that France official postal service launched the first regular drone postal route helps avoid such errors.

Final Answer:
Hence, the first country in the world to use drones for a regular national mail service was France.