Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
name the sorority a.k.a. "sigmas" that was founded in the university of southern california.

### Inputs:
table_name: table, columns: ['Letters', 'Organization', 'Nickname', 'Founding Date', 'Founding University', 'Type']

### Response:
SELECT Organization FROM table WHERE Founding University = University of Southern California AND Type = Sorority AND Nickname = "Sigmas"