The answer you're looking for is A. Podría. When you conjugate a word, you change it based on the ending (unless stated otherwise) Here are the conjugations. Please note, that all of these conjugations are for verbs that don't specify a change otherwise (Ex: Tener or Ser)
I (Yo): Add an "o" to the end for all verbs.
You (Tú): Add "as" for "AR" verbs, or "es" for "ER" and "IR" verbs.
He, she, you, it (Él, ella, usted): Add "a" for "AR" verbs or "e" for "ER" and "IR" verbs.
We (nosotros): Add "amos" for "AR" verbs, "emos" for "ER" verbs, and "imos" for "IR" verbs.
They, you all (Ellos, ellas, ustedes): Add "an" for "AR" verbs, and "en" for "ER" and "IR" verbs.
Therefore making Pordía your answer.
I hope this helps!