A circuit has three nodes connected with R$1=2,$ R$2=4,$ and R$3=6.$ If node $1$ is connected to a $10$V source and nodes $2$ and $3$ are grounded, use Nodal Analysis to calculate the voltage at node $2.$

a$.$

$5$V

b$.$

$10$V

c$.$

$2\mathrm{.}5$V

d$.$

$7\mathrm{.}5$V