Assume that we want to use each thread to calculate two adjacent elements of

a vector addition. What would be the expression for mapping the thread$/$block

indices to the data index $($i$)$ of the first element to be processed by a thread?

$($A$)$ i$=$blockIdx.x blockDim.x $+$ threadIdx.x $+2$;

$($B$)$ i$=$blockIdx.x threadIdx.x $2$;

$($C$)$ i$=($blockIdx$.$x blockDim.x $+$ threadIdx.x$)2$;

$($D$)$ i$=$blockIdx.x blockDim.x $2+$ threadIdx.x;