Secure data sharing in Snowflake allows users to share various objects between Snowflake accounts without physically copying the data, thus not consuming additional storage. Among the options provided, external tables can be shared through secure data sharing. External tables are used to query data directly from files in a stage without loading the data into Snowflake tables, making them suitable for sharing across different Snowflake accounts.
References:
Snowflake Documentation on Secure Data Sharing
SnowPro™ Core Certification Companion: Hands-on Preparation and Practice

The Snowpark-optimized warehouse is designed with significantly higher memory per node, making it ideal for machine learning (ML) training and other memory-intensive workloads. Snowpark-optimized warehouses provide the necessary computational power and memory for complex, large-scale data processing tasks.
Standard and multi-cluster warehouses do not offer the same memory advantage, while the 6XL warehouse is large but not specifically optimized for memory-intensive operations.

Transient tables in Snowflake have a default Time Travel retention period of 1 day, which allows users to access historical data within the last 24 hours. However, transient tables do not have a Fail-safe period. Fail- safe is an additional layer of data protection that retains data beyond the Time Travel period for recovery purposes in case of extreme data loss. Since transient tables are designed for temporary or intermediate workloads with no requirement for long-term durability, they do not include a Fail-safe period by default1.
References:
* Snowflake Documentation on Storage Costs for Time Travel and Fail-safe