Machine$-$to$-$machine $($M$2$M$)$ communication refers to which of the following?

a$.$ Connected devices interacting without human intervention

b$.$ Using values or algorithms to provide data$-$backed decision options

c$.$ The application of scientific knowledge to efficiently solve real$-$world problems

d$.$A procedure that helps organizations evaluate the possible effects that new processes, systems, and products will have on business operations and stakeholders

e$.$ A decentralized recordkeeping technology