Primers $\mathbf{P}, \mathbf{Q}, \mathbf{R}$ and $\mathbf{S}$ have binding sites on the template DNA as depicted in the figure below.


In a polymerase chain reaction (PCR) using all four primers together, the possible number of amplified products of different sizes is:

• A

  $2$
• Correct answer
  B

  $4$
• C

  $3$
• D

  $1$

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