PLEASE HELP 7TH GRADE MATH

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 coefficient matrix represents a system of linear equations that has a unique solution ? options in photo*

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25