Final answer:
Functional obsolescence-curable in residential properties is most often caused by deficiencies. Planned obsolescence is a strategy where goods are designed to be replaced frequently, but there's an increasing focus on sustainability and durable goods that can be repaired or upgraded to last longer.
Step-by-step explanation:
Most functional obsolescence-curable in residential properties is typically caused by some kind of deficiency (Option A). This term refers to aspects of a property that are less than optimal due to missing, outdated, or inadequate features or design, causing the property's value to decrease. In the context of planned obsolescence, manufacturers intentionally design products with a predetermined lifespan, prompting consumers to replace items more frequently, as seen with products like nylon stockings which are prone to runs and cannot withstand many wearings.
However, a movement against this trend advocates for repair over replacement, valuing durability, sustainability, and quality in goods. High-quality goods that are designed to be easily repaired or upgraded can challenge the disposable economy and planned obsolescence, ensuring that products remain useful for longer periods and reduce environmental impact.