Final answer:
The correct answer is 'B' which is 'supe'. In Spanish, 'yo' is the subject which means 'I'. The past tense conjugation of 'saber' would be 'supe' in this case.
Step-by-step explanation:
The correct answer is B which is supe.
In Spanish, the verb 'saber' means 'to know' when it refers to knowledge or facts. In this case, 'yo' is the subject which means 'I' in English. Therefore, the correct conjugation for the verb 'saber' in the past tense would be 'supe' as it matches with the singular first-person form.
For example, you can use it in a sentence like 'Ayer yo supe la verdad sobre el accidente' which translates to 'Yesterday I knew the truth about the accident'.
Learn more about Conjugation of the verb 'saber' in Spanish