user: Question: What is the incumbent for Pennsylvania 15
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Pennsylvania 6', 'Hugh Scott', 'Republican', 1946.0, 'Re-elected', 'Hugh Scott (R) 50.6% Alexander Hemphill (D) 49.4%']
SQL:

assistant: SELECT "Incumbent" FROM "Table" WHERE "District" = 'Pennsylvania 15';