Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| District | Incumbent | Party | First elected | Result | Candidates |
| --- | --- | --- | --- | --- | --- |
| California 1 | Clarence F. Lea | Democratic | 1916.0 | Re-elected | Clarence F. Lea (D) Unopposed |
| California 2 | Harry Lane Englebright | Republican | 1926.0 | Re-elected | Harry Lane Englebright (R) Unopposed |
| California 4 | Florence Prag Kahn | Republican | 1925.0 | Re-elected | Florence Prag Kahn (R) Unopposed |
| California 5 | Richard J. Welch | Republican | 1926.0 | Re-elected | Richard J. Welch (R) Unopposed |
| California 6 | Albert E. Carter | Republican | 1924.0 | Re-elected | Albert E. Carter (R) Unopposed |
| California 7 | Henry E. Barbour | Republican | 1918.0 | Re-elected | Henry E. Barbour (R) Unopposed |
| California 8 | Arthur M. Free | Republican | 1920.0 | Re-elected | Arthur M. Free (R) Unopposed |
| California 9 | William E. Evans | Republican | 1926.0 | Re-elected | William E. Evans (R) Unopposed |
| California 10 | Joe Crail | Republican | 1926.0 | Re-elected | Joe Crail (R) 75.0% John F. Dockweiler (D) 25.0% |
Question:
what's the district with incumbent being richard j. welch
Answer:
California 5