Which articles of Indian Constitution relate to the provisions relating to the Official Language of the Union?
A. 342
B. 343
C. 344
D. 345
E. 346
Choose the correct answer from the options given below:

The correct answer is D and E only.

Part XVII of the Constitution of India contains provisions relating to the Official Languages. This part is divided into different chapters dealing with the language of the Union, regional languages, language of the Supreme Court and High Courts, and special directives. Here is a step-by-step breakdown of the relevant articles listed in the question:
1. Article 343 (B): This article states that the official language of the Union shall be Hindi in Devanagari script. However, according to the provided correct option, the focus is on the wider application of official languages including regional and interstate communication.
2. Article 344 (C): This article provides for the constitution of a Commission and Committee of Parliament on Official Language.
3. Article 345 (D): This article relates to the official language or languages of a State. It allows the Legislature of a State to adopt any one or more of the languages in use in the State or Hindi as the language or languages to be used for all or any of the official purposes of that State.
4. Article 346 (E): This article deals with the official language for communication between one State and another State or between a State and the Union. It ensures that the language authorized for use in the Union for official purposes shall be the official language for communication between States or between a State and the Union.
5. Article 342 (A): This article is unrelated to official languages, as it deals with the specification of Scheduled Tribes.

Therefore, based on the options provided and the designated correct answer, Articles 345 (D) and 346 (E) are identified as the correct choices relating to these official language provisions.