Explain the meaning of the following :a) magnetic field​

A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. ... A permanent magnet′s magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

answer: i'm not sure which is which for i get confused on it all the time but i can tell you that the answer lies with the convex and concave devices. i hope this you. have a good day and best of luck to you!

explanation: