Which country became the seventh member of the South Asia Subregional Economic Cooperation (SASEC) programme on 31 March 2017?

Introduction / Context:
The South Asia Subregional Economic Cooperation programme, known as SASEC, is an initiative that aims to promote regional prosperity through improved connectivity and economic cooperation among member countries. General knowledge questions often focus on membership changes in regional groupings, including which country joined and when. The addition of the seventh member in 2017 is one such fact frequently tested.

Given Data / Assumptions:
- The grouping in question is SASEC.
- The question asks which country became its seventh member on 31 March 2017.
- The options list Myanmar, Bhutan, Nepal, Maldives and Sri Lanka.

Concept / Approach:
Originally, SASEC included a set of South Asian countries. In 2017, the programme expanded its membership by including a Southeast Asian country that has close links to India and South Asia, particularly through connectivity and trade routes. This country is Myanmar, which lies at the junction between South Asia and Southeast Asia, making it a logical and strategic addition to SASEC.

Step-by-Step Solution:
Step 1: Recall that SASEC initially included countries like Bangladesh, Bhutan, India, Maldives, Nepal and Sri Lanka. Step 2: Remember that Myanmar joined the SASEC programme in 2017, expanding the group size to seven. Step 3: Note that Bhutan and Nepal were already members before 2017, so they cannot be the new seventh member. Step 4: Maldives and Sri Lanka were also part of the earlier membership and therefore are not the new entrant asked about. Step 5: Conclude that Myanmar is the country that became the seventh SASEC member on 31 March 2017.

Verification / Alternative check:
Press releases from the Asian Development Bank, which supports the SASEC programme, mention that Myanmar became the seventh member on 31 March 2017. The same information appears in reports discussing India connectivity with Southeast Asia. These consistent references confirm that Myanmar is the correct answer and that it joined SASEC on that date.

Why Other Options Are Wrong:
Bhutan: It was among the founding or early members and therefore not the seventh member added in 2017.
Nepal: It also belonged to SASEC before 2017 and cannot be the new entrant mentioned in the question.
Maldives: Part of the original membership, not the country that joined in March 2017.
Sri Lanka: Another early member of SASEC, not added in 2017 as the seventh member.

Common Pitfalls:
A common pitfall is to assume that only South Asian countries can be members of SASEC and therefore to overlook Myanmar, which is technically a Southeast Asian country. Another mistake is not remembering the original member list and thus guessing randomly among the options. A clear mental link between SASEC expansion and Myanmar role as a bridge between South Asia and Southeast Asia helps avoid this confusion.

Final Answer:
The country that became the seventh member of the South Asia Subregional Economic Cooperation programme on 31 March 2017 is Myanmar.