原因は?
原因は何?
What was the cause?
the primary cause of something
なる原因
その原因は
する原因
a cause
the final cause
What is responsible for the fight?
原因もなく
What was the cause of (his) death?
根本原因.
根本原因.
the root cause
the chief cause―the principal cause
a cause
する原因
その原因は
なる原因
the primary cause of something
原因は?
the final cause
原因もなく
the chief cause―the principal cause
the root cause
原因は何?
What was the cause?
With some cause