Several factors affect the rate of adoption of new products. Most of these factors cause the rate to be higher if there is more of the factor. One of the factors actually slows down the rate of adoption of new products if there is more of this factor. Which of these factors will slow down new product adoption the more there is of it$?$

a$)$ compatibility

b$)$ complexity

c$)$ observability

d$)$ relative advantage

e$)$ trialability