Concept:A direct current dynamo must produce current that flows in one direction only.
Explanation:An alternating current dynamo uses slip rings, which reverse the connection every half turn.
This makes the current change direction, producing alternating current.
To convert it into a direct current dynamo, the slip rings must be replaced with a split ring commutator.
The split ring commutator reverses the external connection at the same time the coil current reverses.
As a result, the current in the external circuit continues flowing in one direction.
Answer:C. slip rings are replaced with split ring commutator