@no_ming and @Dr. Jayanthi Sankaran I think that is looking for correct (C), straight out of Gregory (emphasis mine):
"3.3.3 CVA or Credit Limits? Both. CVA focuses on evaluating counterparty risk at the trade level (incorporating all specific features of the trade) and counterparty level (incorporating risk mitigants). In contrast, credit limits essentially act at the portfolio level by limiting exposures to avoid concentrations. When viewed like this, we see that CVA and credit limits act in a complementary fashion as illustrated in Figure 3.5. Indeed, CVA encourages minimising the number of counterparties an institution would trade with since this maximises the benefits of netting whilst credit limits encourage maximising this number. Hence, CVA and credit limits are typically used together as complementary ways to quantify and manage counterparty risk."-- Gregory, Jon. Counterparty Credit Risk and Credit Value Adjustment: A Continuing Challenge for Global Financial Markets (The Wiley Finance Series) (Kindle Locations 1352-1360). John Wiley and Sons. Kindle Edition.