The answer is A) viajé
Explanation: This sentence is in simple past tense. And the correct conjugation for the first person singular pronoun I (yo) is viajé. I'll leave you the complete pronouns' conjugation below.
YO (I) = viajé
TÚ (you)= viajaste
ÉL (he)= viajó
ELLA (she) = viajó
NOSOTROS (we)= viajamos
USTEDES (you)= viajaron
ELLOS (they)= viajaron
NOTES:
- The Spanish conjugation with almost all the verbs with pronouns USTEDES and ELLOS are the same.
- The accent (´) in words represents past tense.