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$.$ Technological and competitive

b$.$ Competitive and social

c$.$ Social and technological

d$.$ Regulatory and competitive

e$.$ Economic and technological