Which of the following is NOT one of the three main types of triggers that Dataflow supports?

Which of the following is NOT one of the three main types of triggers that Dataflow supports?
A . Trigger based on element size in bytes
B . Trigger that is a combination of other triggers
C . Trigger based on element count
D . Trigger based on time

Answer: A

Explanation:

There are three major kinds of triggers that Dataflow supports: 1. Time-based triggers 2. Data-driven triggers. You can set a trigger to emit results from a window when that window has received a certain number of data elements. 3. Composite triggers. These triggers combine multiple time-based or data-driven triggers in some logical way

Reference: https://cloud.google.com/dataflow/model/triggers