In October of $2001,$ there were approximately $15$ million cell$-$phone subscribers in the Australia. That number increases by $4,000$ daily. There are $\mathrm{.}8$ million payphones that receive little or no usage. Pay$-$phone providers are hoping to find some way to make use of these idle phones. This is one way that $\_\_\_\_$ forces have jointly influenced marketers.

a$.$

Social and technological

b$.$

Economic and technological

c$.$

Regulatory and competitive

d$.$

Competitive and social

e$.$

Technological and competitive