Consider the following in respect of sets A and B : 1. $(\mathrm{A}-\mathrm{B}) \cup \mathrm{B}=\mathrm{A}$ 2. $(\mathrm{A}-\mathrm{B}) \cup \mathrm{A}=\mathrm{A}$ 3. $(A-B) \cap B=\phi$ 4. $A \subseteq B \Rightarrow A \cup B=B$ Which of the above are correct?

• A

  1,2 and 3
• Correct answer
  B

  2,3 and 4
• C

  1,3 and 4
• D

  1,2 and 4

Solution

Venn diagram
from, Venn diagram we can observe that $\mathrm{A}-\mathrm{B}$ is the shaded part. $\begin{aligned} & (A-B) \cup A=A \\ & (A-B) \cap B=\phi \\ & A \subseteq B \Rightarrow A \cup B=B \end{aligned}$

Hence, the correct answer is option: 'B'.