Until 2018, what TV Western held the record for most prime-time episodes?

Here is the question :

UNTIL 2018, WHAT TV WESTERN HELD THE RECORD FOR MOST PRIME-TIME EPISODES?

Here is the option for the question :

Walker, Texas Ranger
Bonanza
Gunsmoke
Rawhide

The Answer:

And, the answer for the the question is :

GUNSMOKE

Explanation:

[STC009869]. From 1955 through 1975, ‘Gunsmoke’ was broadcast on CBS. Over the course of its staggering 20-year existence, the show aired a staggering 635 episodes, which was the most of any prime-time show at the time. Before the show extended to a full hour for the following 14 years, the first six seasons comprised of episodes that were just a half an hour long. The number of ‘The Simpsons’ episodes that were broadcast during prime time was surpassed in 2018.