Answer:
A.
Step-by-step explanation:
An Informative essay is a type of essay that provides information about something. The purpose of such essays is to educate its audience. Informative essays performs functions such as it may define a term, or provide 'how-to-do', etc.
An introduction of an informative essay should contain the background of the topic that is about to be elaborated in the essay later. The introduction also consists of a thesis statement that announces the topic of the essay.
So, for writing the introduction of an informative essay about a turning point is should consist of the background details as well as the thesis statement.
So, the correct answer is option A.