The dependent source in the following diagram is:

In the given figure, the current source depends upon another current i_o. Therefore, the symbol represents a current controlled current source.

Electrical sources

1) Independent sources:  A source that maintains a voltage or current that is unaffected by any other voltage or current present in the circuit is known as an independent source.

2) Dependent sources: A dependent source is a current or voltage source whose value is not fixed. Instead, the value depends on some other circuit current or voltage.

There are four possible dependent sources:

1. Voltage-controlled voltage source (VCVS)
2. Voltage-controlled current source (VCCS)
3. Current-controlled current source (CCCS)
4.  Current-controlled voltage source (CCVS)