Taira and Minamoto (answers 1 and 4) are two of the greatest warrior clans of Japanese Samurais. Both clans fought each other during 12th century persuing the control of Japan.
Finally, the victory was for Minamoto clan and Taira warriors commited one of the largest mass suicede in Samurai History.
It’s important to add that Heian (answer 2) is not a Samurai clan, it’s the name of an important period in Japanese history and Khmer (answer 3) is actually a language of Cambodia.
