Using a SIPOC in a Y$=$f$($x$)$ context which of the following statement applies when attempting to understand the key X$\text{'}$s that drive Y$?$

a$.$ X corresponds to Input and Output measures, Y corresponds to process measures

b$.$ X corresponds to process and output measures, Y corresponds to Input measures

c$.$ X corresponds to input and Process measures, Y corresponds to Output measures

d$.$ X corresponds to Input measures, Y corresponds to Output measures