How are view-through conversions counted?

They’re counted as conversions that are recorded when repeat users view but don’t interact with an ad, then later convert.
They’re counted as conversions that are recorded when users view but don’t interact with an ad, then later convert.
They’re counted as conversions that are recorded when users view and interact with an ad, then never convert.
They’re counted as conversions that are recorded when new users view and interact with an ad, then later convert.