What is causing the line protocol on this interface to be shown as down?

Refer to the exhibit.

A network engineer investigates a recent network failure and notices that one of the interfaces on the switch is still down.

What is causing the line protocol on this interface to be shown as down?
A . There is a layer 1 physical issue.
B . There is a speed mismatch on the interface.
C . The interface is configured as the target of the SPAN session.
D . The interface is configured as the source of the SPAN session.
E . There is a duplex mismatch on the interface.

Answer: C

Explanation:

With the SAPN destination port, the state of the destination port is up/down by design. The interface shows the port in this state in order to make it evident that the port is currently not usable as a production port. This is the normal operational state for SPAN destinations. Reference: http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015c61 2.shtml