Which solution will meet these requirements?

Explanations:

Setting the reserved concurrency to match the number of concurrent requests allowed by the third-party service ensures that the Lambda function does not exceed the request limit, thereby preventing rate-limiting errors. This effectively controls the maximum number of concurrent executions and helps manage the rate of requests sent to the service.

Decreasing the memory allocated to the Lambda function does not address the rate-limiting issue. Memory allocation affects the function’s performance and execution time but has no direct impact on the number of requests sent to the third-party service. Rate limiting is related to the request rate, not memory usage.

Provisioned concurrency helps in managing the warm-up time for the Lambda function but does not limit the number of concurrent executions. The function can still exceed the rate limits of the third-party service if it receives too many requests at once. Therefore, this option does not effectively prevent rate-limiting errors.

Increasing the timeout value for the Lambda function will not prevent rate-limiting errors. It only allows the function to run longer before timing out, which does not mitigate the problem of exceeding the request limit imposed by the third-party service. Rate limiting is based on the frequency of requests, not the duration of individual executions.