Which term refers to materials that sense changes in the environment and respond to them?

• A. Composite materials
• B. Smart materials
• C. Thermochromic ink
• D. Polymorph

Answer: (B)

The main idea here is materials that can sense changes in their surroundings and automatically respond by changing a property of themselves. Smart materials do exactly that: they react to stimuli like temperature, light, electric or magnetic fields, or mechanical stress, and alter something useful—shape, color, stiffness, or stiffness, among others. For example, shape memory alloys shift back to a predefined shape when heated; electrochromic materials change their tint when a voltage is applied; and piezoelectric materials generate an electrical signal or move under mechanical pressure. This built-in sensing and responding capability makes them distinct from other materials.

Composite materials are engineered for improved strength or other traits by combining different substances, but they don’t inherently sense or respond to environmental changes. Thermochromic ink changes color with temperature, but that’s a passive property change rather than an active sensing-and-responding behavior. Polymorph is a thermoplastic used for modelling, not defined by environmental sensing or adaptive response.