Which of the following pairs of sets are disjoint?
${1, 2, 3, 4}$ and ${x : x \text{ is a natural number and } 4 \le x \le 6}$

$A$ class has $175$ students. The following data shows the number of students opting for one or more subjects: Mathematics $100$,Physics $70$,Chemistry $40$; Mathematics and Physics $30$,Mathematics and Chemistry $28$,Physics and Chemistry $23$; Mathematics,Physics,and Chemistry $18$. How many students have opted for Mathematics alone?

Which of the following pairs of sets are disjoint?
$A = \{a, e, i, o, u\}$ and $B = \{c, d, e, f\}$

Let $A = \{a, b, c\}, B = \{b, c, d\}, C = \{a, b, d, e\}$. Then $A \cap (B \cup C)$ is

The shaded region in the given figure is

If $A = \{3, 5, 7, 9, 11\}$,$B = \{7, 9, 11, 13\}$,$C = \{11, 13, 15\}$,and $D = \{15, 17\}$,find $A \cap B$.