Sure! Here is an SEO optimized HTML answer for the LINQ category interview question "How can you implement a left outer join in LINQ?":

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Implementing Left Outer Join in LINQ

In LINQ, you can implement a left outer join using the DefaultIfEmpty() method along with the join keyword. Here's an example:

var result = from itemA in listA
             join itemB in listB
             on itemA.Key equals itemB.Key into gj
             from subItemB in gj.DefaultIfEmpty()
             select new { ItemA = itemA, ItemB = subItemB };

This code snippet demonstrates how to perform a left outer join between two lists listA and listB based on a common key. The DefaultIfEmpty() method ensures that all elements from the left list are included in the result, even if there is no matching element in the right list.

```

This HTML snippet provides a concise and SEO-friendly explanation of how to implement a left outer join in LINQ for a programming interview. It includes a code example and explanation to help readers understand the concept effectively.