Name two product with an inelastic demand​

Joe pays ann to mow his lawn and ann mows vanna's lawn by mistake. vanna peers out her window and sees ann mowing, yet says nothing to ann about her mistake since vanna needs to have her lawn mowed. when ann approaches vanna for payment, vanna refuses, arguing that she never asked ann to mow her lawn. under these circumstances, ann can recover payment from vanna under:

Later movers do not face: entrenched competitors. reduced uncertainty over technologies. high growth markets. lower market uncertainty.

How has apple been able to sustain its competitive advantage in the smartphone industry? a. by reducing its network effects b. by targeting its new products and services toward laggards c. by driving the price for the end user to zero d. by regularly introducing incremental improvements in its products