The correct answer is A.

A. This solution meets the requirements because it allows the company to create different usage plans for each customer, with different request quotas and time periods. The usage plans can be associated with API keys, which can be distributed to the users of each customer. The API Gateway REST API can invoke the Lambda function using a proxy integration, which passes the request data to the function as input and returns the function output as the response.This solution is scalable, secure, and cost-effective12

B. This solution is incorrect because API Gateway HTTP APIs do not support usage plans or API keys.These features are only available for REST APIs3

C. This solution is incorrect because it does not provide a way to enforce request quotas for each customer. Lambda function aliases can be used to create different versions of the function, but they do not have any quota mechanism.Moreover, this solution exposes the Lambda function URLs directly to the customers, which is not secure or recommended4

D. This solution is incorrect because it does not provide a way to differentiate between customers or users. AWS WAF rate-based rules can be used to limit requests based on IP addresses, but they do not support any other criteria such as user agents or headers.Moreover, this solution adds unnecessary complexity and cost by using an ALB and a VPC56