Which of the following is the best practice related to SSIS?

When a question frames several individual technical statements as options and also offers an "all of the mentioned" choice, each statement has to be checked on its own merits against the authoritative guidance for that technology -- the correct choice is whichever statement(s) actually hold up, and if more than one turns out to be genuinely correct, the exhaustive option is the one that reflects that.

Checking each statement here against Microsoft's own published guidance on SQL Server Integration Services (the SQLCAT team's "Top 10 SQL Server Integration Services Best Practices"): "Plan for capacity by understanding resource utilization" is documented there as monitoring the CPU, memory, I/O, and network usage of running packages. "SSIS is an in-memory pipeline, so ensure that all transformations occur in memory" is documented there as keeping transformations from spilling to disk. "Baseline source system extract speed" is documented there as measuring how fast you can read from the source, since a pipeline cannot transform data faster than it can read it.

Cross-checking each statement individually against that source:

• The resource-utilization statement matches the guidance on monitoring CPU, memory, I/O, and network usage while packages run.

• The in-memory-transformation statement matches the guidance on keeping the transform phase within memory and watching for disk spooling.

• The source-extract-speed statement matches the guidance on measuring the source system's read throughput as the ceiling on the whole pipeline.

Since all three statements independently check out against the same authoritative guidance and none contradicts another, no single one of them can be singled out as "the" one correct practice -- the accurate answer is the option that covers all of them.