2 Answers

I am sorry that I can not answer your question.  Try using google.  Some folks here feel we should not help with homework but after all what is a question forum for?  Sadly I am math dumb. I do hope you find your answer.

I believe the correct answer is "A", because the circle at the 7.5 value is open. This indicates the value 7.5 is NOT included, which would be m < 7.5 (the value of "m" is less than 7.5)
In answer "B", the circle at 7.5 is full, which implies the value of m is less than or EQUAL to 7.5.
In "A" and "B", the value of the pink line decreases, and I am assuming "m" is the pink line. 
In answers "C" and "D", the value of the pink line (m)  either starts at or exceeds 7.5.