a little from column A, a little from column B

The phrase originates from the structure of American Chinese restaurant menus during the mid-twentieth century. These menus typically organised combination entrees into a table with sections labelled Column A and Column B.

The customer was instructed to select one item from each section, commonly phrased as Choose one from Column A and one from Column B. The idiom retains this binary structure to describe a situation involving two distinct options or causes.