Correct Answer: C

• Option A is incorrect because Cloud Spanner, while supporting high-speed reads and writes, is not the most economical solution for storing 15 petabytes of data. The addition of an in-memory cache may improve speed but does not address the cost implications.
• Option B is incorrect because Cloud Storage is not optimized for high-speed reads and writes of small data pieces, despite being cost-effective for large data volumes. Cloud CDN can enhance speed but does not fully meet the requirements.
• Option C is correct because Cloud Bigtable is designed for high-speed reads and writes at scale, supports a simple schema, and is cost-effective for large data amounts. It allows flexibility in business logic implementation.
• Option D is incorrect because BigQuery is optimized for analytics and not for real-time data processing or high-speed reads and writes.

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