Answer: BigQuery

To support an online marketing analytics and reporting application that needs to manage hundreds of terabytes of data, the best choice among the options provided is BigQuery. BigQuery is Google Cloud's fully-managed, petabyte-scale, low-cost analytics data warehouse. It is designed for analyzing large datasets quickly using SQL queries. While Cloud SQL is a good option for relational databases, it is more suited for smaller scale applications. Cloud Spanner is a globally distributed database service that is highly scalable but may be overkill for this specific use case. Bigtable is a NoSQL database service designed for large analytical and operational workloads, but it is not a relational database, which is a requirement for this scenario.

Author: LeetQuiz Editorial Team