What is the most common option for fighting radiation?

Raveena is making a professional presentation for a newly launched product of her company. she wants to incorporate the following features in her presentation. a) to add serial numbers in each slide b) to add name of her company on top of each slide. c) to add the picture of her product on the second slide(the picture of her product is stored on her computer) write the commands/features of her presentation tool using which she can perform the above operations.

Which of these is most responsible for differences between the twentieth century to the twenty-first century?

Hey i just logged on and one of the moderators deleted a bunch of my answers to questions, even though the answers were right and the people it doesn't make sense but if anyone wants to talk about anything just message me lol (this is super random lol)