In the late nineteenth century, which of these factors made a major impact on the culinary arts?

the use of heat and open fires for cooking

the application of techniques like mass production

the introduction of earthenware such as clay vessels

the discovery of the technique of roasting raw foods

the application of techniques like mass production Let's look at the available options and see what makes sense. the use of heat and open fires for cooking - This sounds like the discovery of fire and as such it happened a long time before the nineteenth century. Wrong answer. the application of techniques like mass production - This one looks promising. We'll take if the other 3 options are just plain silly. the introduction of earthenware such as clay vessels - This is more recent than the discovery of fire. But it's still a long time ago. Literally thousands of years BC. So wrong answer. the discovery of the technique of roasting raw foods - Another discovery that happened thousands of years ago. So also the wrong answer. So of the 4 choices, 3 of them happened literally thousands of years ago and so well before the nineteenth century. That leaves only 1 viable choices, so the answer is "the application of techniques like mass production"