Return on Advertising Spend $($ROAS$)$ is a marketing metric that measures the efficacy of a digital advertising campaign. ROAS is a valuable metric in that it provides insight into the profitability of a campaign and helps to inform decisions around budget allocation and campaign optimization. To calculate ROAS, an advertiser must know which of the following?

CTR and conversion rate

CTR and total revenue

Total ad spend and total profit

Total ad spend and CTR