To optimize a query activity that is currently timing out, a developer can use the following strategies:

Use Primary key(s) on fields used in joins (C) - Ensures that the join operations are efficient by utilizing indexed fields.

Use intermediate tables to stage data (D) - Breaks down complex queries into simpler steps, improving manageability and performance.

Only update records that have changed since last execution (E) - Reduces the amount of data processed by focusing only on changes since the last query run.