Which set is the subset of all given sets

Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$

$\varnothing$

Examine whether the following statements are true or false :

$\{ a,b\}  \not\subset \{ b,c,a\} $

Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?

$\{ 3,4\}  \in A$

Which of the following are sets ? Justify your answer.

The collection of all even integers.

Write the following sets in roster form :

$\mathrm{E} =$ The set of all letters in the world $\mathrm{TRIGONOMETRY}$