Assertion $(A)$: Both rhombic and monoclinic sulphur have $S_8$ molecules.
Reason $(R)$: They have planar structure.
The correct option among the following is:

• A
  $A$ is true, $(R)$ is true and $(R)$ is the correct explanation for $(A)$
• B
  $A$ is true, $(R)$ is true but $(R)$ is not the correct explanation for $(A)$
• C
  $A$ is true but $(R)$ is false
• D
  $A$ is false but $(R)$ is true