Ductility is defined as which of the following?

• A. The ability to resist plastic deformation.
• B. The ability to deform under tensile stress.
• C. The ability to conduct electricity.
• D. The ability to corrode easily.

Answer: (B)

Ductility is the ability to undergo plastic deformation under tensile stress. In a tensile test, a ductile material can yield, neck, and elongate significantly before it fractures, which is why such materials can be shaped or formed without cracking. This behavior is quantified by measures like percent elongation or reduction of area. The described option matches this behavior—the ability to deform when pulled. The other statements refer to properties outside this mechanical behavior: resisting plastic deformation would imply low ductility or brittleness, while conducting electricity or corroding are not about how a material deforms under load.