The correct answer is B, which states that an AWS Enterprise Support plan includes designated support from an AWS technical account manager (TAM). A TAM serves as a single point of contact for customers, providing personalized guidance and assistance to optimize their AWS environment, resolve technical issues, and achieve their business goals. The TAM works closely with the customer to understand their specific needs and offers proactive support, architectural guidance, and best practices recommendations. The other options are incorrect because A refers to AWS Partner Network support, which is not included at no cost with an Enterprise Support plan. Option C is incorrect as AWS does not provide on-site support from engineers as part of the Enterprise Support plan. Option D is incorrect because AWS Config is a service for assessing, auditing, and evaluating the configurations of AWS resources, but it is not a benefit of the Enterprise Support plan itself.