اگر $A=\left\{ 1\,,\,\,\left\{ 1\,,2 \right\}\,,\,\left\{ 1 \right\}\,,\,\left\{ 2 \right\} \right\}$ کدام گزینه صحیح نیست؟
$\left\{ 1\,,\,2 \right\}\subseteq A$
2 )
$\left\{ 1 \right\}\in A$
3 )
$\left\{ 1\,,\,2 \right\}\in A$
4 )
$\left\{ {} \right\}\subseteq A$