If the events "owns a car" (let's denote it as A) and "owns a pet" (denote it as B) are independent, then the conditional probability P(B | A) can be calculated using the rule of independence. For independent events, the following relationship holds:
\[ P(B | A) = P(B) \]
This means that knowing event A (owns a car) does not change the probability of event B (owns a pet).
Given this, the correct answer is:
P(owns a pet)