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

### Instruction:
What is the surface when the us open is the championship in the year 1979?

### Inputs:
table_name: table, columns: ['Outcome', 'Year', 'Championship', 'Surface', 'Partner', 'Opponents', 'Score']

### Response:
SELECT Surface FROM table WHERE Championship = US Open AND Year = 1979