The correct answer to your question is A, the early nineteenth century. people previous this time learned that they need to clean wounds and that it is extremely painful to do surgery to those who are awake, but they didn't have the tools or the technology to develop things that would do this. it wasn't until the early nineteenth century that many crucial elements to the medical field, such as antiseptic and anesthesia, were developed.
let me know if you have any further questions
:)
I would choose B. due to the fact someone is sitting there with them watching them eat as they eat as well. in A. you have no clue if your kid will actually buy food even if there is time.
in C. they could feed it to the dog or throw it away again you don't know due to no one else being their.
and in D. will they buy food? you don't know.
Answer: Independent variable
Explanation:
Independent variable can be defined as the variable that is changed or controlled in the experiment. The independent variable is changed during the experiment in order to see the effect of dependent variable which changes due to change in the independent variable.
Here, the given statement is independent variable in which the no one or other students in room would learn students.
This is independent variable as dependent variable will change based on independent variable.
