For any two positive integers $a$ and $b$,what is the relationship between their $HCF$ and $LCM$? $\text{HCF}(a, b) \times \text{LCM}(a, b) = \text{?}$

• A
  $a + b$
• B
  $a \times b$
• C
  $a - b$
• D
  $a \div b$