You got to "insert" and then you go to "shapes" and then you find the symbol you like and you drag and drop it onto the page. Then you can resize to the size and angle you would like it at.
Answer:
I think the answer is formulas
The answer is the first response, by order of elimination, you can eliminate the rest.
HTML is a programming language that is used to design websites. You don't need to program a website to make a post on instagram, especially if you are using the app.
If you check the app store on your phone, you can find instagram in the app store, which lets you access it from your mobile device. Thus, the third option is wrong.
Finally, just read the description of instagram. It was made for sharing pictures, so the last option is wrong.