In BPMN, a task box with asmall envelope iconin its corner represents aMessage-related Task. In the standard notation, that icon on a plain task (like A) is used most commonly for aSend Task:
ASend Task: when executed, itsends a messageand then completes, allowing the process to continue along the outgoing sequence flow.
The following activity (here,B) begins after A completes.
There is no indication of additional work after the message within A beyond what’s included in that send action itself; and there is no separate incoming Message Flow that would indicate a Receive Task.
Evaluating the options:
A. Send a message, then immediately perform B.This matches the behavior of aSend Task followed by another taskvia a sequence flow.
B. Receive a message, then immediately perform B.That would normally be modeled as aReceive Taskwith message flow from an external participant; the diagram only indicates an internal message task.
C. Send a message and perform some work in A, then perform B.In BPMN, the “work in A”isthe sending itself; extra work would typically be modeled as separate tasks.
D. Receive a message and perform some work in A, then perform B.Combines the incorrect assumption of a Receive Task with extra unspecified work.
Thus, the diagram depicts:Task A sends a message, then the process continues with B, which is optionA.
