To become a Grade B officer in the Reserve Bank of India (RBI), you must meet certain eligibility criteria and pass through a selection process. Here's a general outline of the steps involved:

1. Educational Qualification: You need to have a minimum of a bachelor's degree with at least 60% marks (50% for SC/ST/PWD) or an equivalent grade in aggregate from a recognised university.

2. Age Limit: Typically, the age limit for RBI Grade B officer recruitment is between 21 and 30 years. There are age relaxations for certain categories such as SC/ST/OBC/PWD.

3. Selection Process: The selection process usually consists of three phases:

• Phase I - Preliminary Examination: This phase consists of objective-type questions covering subjects like General Awareness, English Language, Quantitative Aptitude, and Reasoning. It serves as a screening test.
• Phase II - Main Examination: This phase comprises both objective and descriptive-type questions. It includes Economic & Social Issues, Finance & Management/Economics/Statistics, English (Writing Skills), and an optional subject.
• Phase III - Interview: Candidates who clear the main examination are called for an interview. This phase evaluates your communication skills, leadership qualities, and overall suitability for the job.

Applying for this exam is how you become an officer in RBI.

Remember, the process and eligibility criteria may vary slightly based on RBI's official notifications, so it's crucial to refer to the latest information provided by RBI during the recruitment period.