D. Activating Background knowledge
In general, an essay should have an introduction (one paragraph), a body (number of paragraphs depends on the topic and how many words it shoud have, but it should have at least 3 paragraphs) and a conclusion (one paragraph).
As for the content, you can write about the topic in general, but it would be easier if you chose a specific example. It can be a true story, or you can make one up, since it is far more important how you write it, than whether it is true or not. One of the easiest examples would be a parent or grandparent.
You could start by saying that a great number of people pass through a persons life and that we look at other peoples behaviour, replicate the things we like and dismiss the ones we don't. Everyone looks up to someone, especially when we are young and impressionable and at different points of our lives we admire different people. If you are writing about a family member, you should say that there was one person that you especially admired and always looked up to. You could write about your early childhood and how impressed you were by that person, how wise/interesting/brave you thought they were. You should mention the things that that peson taught you, how he/she affected the decisions you made. Later, you could write about how you grew up, changed, and how you see things differently, but that person is still your hero and that you wouldn't be the person that you are today without him/her.
Answer:
it has caused a gradual heating heating of earth's atmosphere
