1 or 2?

Look at the picture.
Thank u!

When using the linear combination metho e linear combination method to solve a system of linear equations, the four options are:

An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .

Which type of graph would allow us to quickly see how many students between 100 and 200 students were treated?