The CUSTOM tier for Cloud Machine Learning Engine allows you to specify the number of which types of cluster nodes?

The CUSTOM tier for Cloud Machine Learning Engine allows you to specify the number of which types of cluster nodes?
A . Workers
B . Masters, workers, and parameter servers
C . Workers and parameter servers
D . Parameter servers

Answer: C

Explanation:

The CUSTOM tier is not a set tier, but rather enables you to use your own cluster specification. When you use this tier, set values to configure your processing cluster according to these guidelines:

You must set TrainingInput.masterType to specify the type of machine to use for your master node.

You may set TrainingInput.workerCount to specify the number of workers to use.

You may set TrainingInput.parameterServerCount to specify the number of parameter servers to use. You can specify the type of machine for the master node, but you can’t specify more than one master node.

Reference: https://cloud.google.com/ml-engine/docs/training-overview#job_configuration_parameters