Q.SIDBI, established in 1990, is the apex institution mainly for:
(A) Promoting exports
(B) Financing and developing the micro, small, and medium enterprise (MSME) sector
(C) Developing industrial estates and factory sheds
(D) Registering small units at the district level

The word 'bank' in SIDBI's full name points to its core role — it is a financing body for small industry.

It provides refinance to banks and SFCs that lend to small units and direct finance to small and medium enterprises. Export promotion, infrastructure development, and district-level registration are done by other institutions.

Section c states that SIDBI (the Small Industries Development Bank of India), set up in 1990 with its head office at Lucknow, is the apex (topmost) financial institution for the promotion, financing, and development of the micro, small, and medium enterprise (MSME) sector — in simple words, the chief bank for small industry. This makes option (B) correct.

SIDBI does this mainly by providing refinance to banks and State Financial Corporations that lend to small units, and by giving direct finance to well-run small and medium units for expansion and modernisation.

The other options describe the work of other institutions: promoting exports (A) is the role of FIEO; developing industrial estates and factory sheds (C) is done in Odisha by IDCO; and registering small units at the district level (D) is a function of the District Industries Centre. SIDBI's identity is as a financier, which is why its name ends in 'Bank'.

Do not mix up the roles of institutions. SIDBI = finance; FIEO = exports; IDCO = infrastructure; DIC = district-level single window. The name 'Development Bank' is the clue that SIDBI is about finance.