Q.Which of the following is a SELECTIVE (qualitative) method of credit control?
(A) Bank rate
(B) Open market operations
(C) Margin requirements
(D) Cash reserve ratio

Three of these change the total amount of credit; only one targets the use of credit against a particular security.

Section c draws the key distinction: quantitative methods control how much credit is created in the whole economy, while selective (qualitative) methods control for what purpose credit is used.

Bank rate (A), open market operations (B), and the cash reserve ratio (D) are all listed in Section d as quantitative tools — they raise or lower the total volume of credit across the entire economy without singling out any particular use. …

Remember which family each tool belongs to. Quantitative: bank rate, OMO, CRR, SLR, repo. Selective: margin requirements, consumer-credit regulat …