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

### Instruction:
Who sponsored Greg Biffle's win on April 14?

### Inputs:
table_name: table, columns: ['Season', 'Date', 'Winning Driver', 'Car #', 'Sponsor', 'Make', 'Distance', 'Avg Speed', 'Margin of Victory']

### Response:
SELECT Sponsor FROM table WHERE Winning Driver = greg biffle AND Date = april 14