T-SQL Puzzle 2 - CASE Statement

What will be the output of below Query:

DECLARE @f as int

SET @f = 1
SELECT CASE 1
    WHEN @f THEN 'First'
    WHEN @f THEN 'Second'
    ELSE 'Nothing' END
AS CaseStmt

Below are the options:
1. First
2. Second
3. Nothing
4. No records
5. syntax Error