Which expression returns the first integer parse error instead of silently dropping inval…

Which expression returns the first integer parse error instead of silently dropping invalid fields?

1. fields.iter().map(|s| s.parse::<i32>()).collect::<Result<Vec<_>, _>>()
2. fields.iter().filter_map(|s| s.parse::<i32>().ok()).collect::<Vec<_>>()
3. fields.iter().map_while(|s| s.parse::<i32>().ok()).collect::<Vec<_>>()
4. fields.iter().flat_map(|s| s.parse::<i32>()).collect::<Vec<_>>()