The graphs representing typical engineering stress vs$.$ engineering strain curves for four different polymers in a tensile test is presented below. For each polymer, indicate the following points: tensile strength, stress at break, strain at break, the elastic region $($where the elastic modulus can be calculated$).$

Based on the graph above, answer the questions below $($justify your answers$)$: Which material has the lowest elastic modulus?

Which material has the greatest toughness, and how can you tell?

Which material has the highest ductility?

Calculate the tensile stress in a polyamide fishing line of diameter $0\mathrm{.}46$ mm which a fish is pulling with a force of $25$ N $.$