Salesforce Consumer Goods Cloud allows for the creation of custom Visit Recommendation strategies using two primary methods: Salesforce Flow or a custom Apex class. Flow Builder is the recommended declarative tool for building complex, scalable automation and business logic. It enables administrators and consultants to create sophisticated strategies that can query multiple objects and apply business rules to generate recommendations without writing code. This approach is highly scalable and more maintainable by a wider range of personnel than a code-based solution, making it the optimal choice for NTO's requirements.

A. Build the strategy using Workflows: Workflow Rules are a legacy automation tool being retired by Salesforce and do not have the capability to generate the complex VisitRecommendationInfo objects required for this feature.

C. Build the strategy using an Apex class: While using an Apex class is a valid and scalable method, Flow is the preferred low-code/declarative approach. It should be used unless the strategy's complexity exceeds Flow's capabilities, which is not indicated in the question.

D. Build the strategy using Process Builder: Process Builder is also a legacy automation tool being retired. It lacks the necessary functionality to create Visit Recommendation strategies and is less performant and scalable than Flow.

1. Salesforce Help, Consumer Goods Cloud Developer Guide, VisitRecommendationStrategy Interface: "To create your own logic for visit recommendations, create an Apex class that implements the cgcloud.VisitRecommendationStrategy interface." This reference validates that Apex is a possible, though not always preferred, method.

2. Salesforce Help, Consumer Goods Cloud Implementation Guide, "Create a Visit Recommendation Strategy": "You can create a visit recommendation strategy by using a flow or an Apex class." This section explicitly lists the two supported, scalable methods for creating a custom strategy.

3. Salesforce Help, Consumer Goods Cloud Implementation Guide, "Create a Flow for Visit Recommendations": "Create a flow that fetches data from various objects and recommends visits... The flow must have a collection variable of the Apex-defined data type VisitRecommendationInfo as output to store the visit recommendations." This document provides direct evidence for using Flow Builder as the primary declarative tool for this purpose.

4. Salesforce Architects, "Record-Triggered Automation Decision Guide": This guide outlines the reasons for choosing Flow over legacy tools like Process Builder and Workflow Rules, stating, "Flow is the future of low-code automation on the Salesforce Platform... We recommend that you build all new automations in Flow." This supports the deprecation of options A and D and the preference for B.