Which of the following guidance can help a client reduce their fraud rates?

Including Stripe.js on every page can significantly contribute to reduced fraud rates because it enhances the security of payment transactions. Stripe.js is a JavaScript library that helps securely handle credit card information in a way that complies with PCI (Payment Card Industry) standards. By embedding Stripe.js, sensitive card details are tokenized and transmitted directly to Stripe's servers, minimizing the risk of interception by malicious actors. This secure processing helps protect against various types of fraud, such as card data theft or fraudulent chargebacks.

The other options, while potentially beneficial in different contexts, do not directly influence fraud prevention in the same manner. For instance, implementing a rewards program for referrals may encourage customer loyalty but does not address security issues. Focusing on offline marketing strategies might help drive business, but it won't protect against fraud in the online transaction process. Similarly, reducing checkout steps can improve user experience and possibly conversion rates, yet it can also open up risk factors if not combined with robust security measures like those provided by Stripe.js.