D. It is used to add sound effects.
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Answer:
STP mainly uses 5 states in a network, in which some states are replaced in RSTP which improves the time efficiency.
Explanation:
STP mainly uses five states i.e.  Learning, Listening, Blocking, Disabling and Forwarding to overcome the problem of collision in a network.  
RSTP replaced the three states of STP i.e listening, learning, and blocking by Discarding, which results in the time efficiency as compared to STP.  
As STP takes minutes to complete the network inter connectivity, RSTP completes it in seconds.
This is one of the main reason why an administrator want to change to RSTP.
 
        
             
        
        
        
Based on the contextual situation, the cable stations across the country from 8:00 p.m. to 10:00 p.m., or during <u>Late-fringe time</u>.
<h3>What is Late-Fringe Time?</h3>
Late Fringe time is a term used in television that describes the television hours that follow the prime time.
Generally, the prime period is usually between 8:00 p.m. to 10:00 p.m., while the Late Fringe time is around 11 p.m. to 1 a.m.
Hence, in this case, it is concluded that the correct answer is "<u>Late-Fringe period."</u>
Learn more about Television hours here: brainly.com/question/1006994