A Brutus is ambitious for power of his own
She is supporting an inference from the text. An inference is something that is implied, and the person saying they've "witnessed much fighting" infers that they're old, whereas "I am wounded with iron" can be taken to mean he's been wounded by a weapon like a sword.
because, it is easier to use plants or things of that type other than using human trials which can be lethal if done wrong.
Emphasis means “special importance, value, or prominence given to something.” or stress laid on a word or words to indicate special meaning or particular importance. An example is a baby learning how to talk in a month and have a lot of emphasis on her. Emphasis can also mean to focus or like bring attention also surprise.