$-$ Set $\{1,2,3,4,5,6,7,8\}($R$1|$ a divides b$)($R$2|$ a is a multiple of b$)$

$-$ a$.$ Adjacency matrix for R$1$

$-$ b$.$ Adjacency matrix for R$2$

$-$ c$.$ R$1$R$2$

$-$ d$.$ Is R$1$R$2$ reflexive?