Answer:
C. -> Saber
Explanation:
You can see the stem change from "a" to "up" in the preterite tense.
Present Simple tense of Saber (to know)
Yo sé
Tu sabes
Él/Ella sabe
Nosotros sabemos
Vosotros sabéis
Ellos/ellas saben
Perfect Preterite Simple tense of Saber (to know)
Yo supe
Tu supiste
Él/ella supo
Nosotros supimos
Vosotros supisteis
Ellos/ellas supieron
Native speaker over here.
