Match the diseases in Column $I$ with their respective causes given in Column $II$:

Column $I$	Column $II$
$i$. Alzheimer's disease	$a$. Oversecretion of Growth Hormone from pituitary gland in adults.
$ii$. Diabetes mellitus	$b$. Degeneration of dopamine-producing neurons in $CNS$.
$iii$. Acromegaly	$c$. Underactivity of Beta cells of pancreas.
$iv$. Parkinson's disease	$d$. Degeneration of cholinergic and other neurons in $CNS$.

Select the correct option from the following:

• A
  $i-d, ii-c, iii-b, iv-a$
• B
  $i-d, ii-c, iii-a, iv-b$
• C
  $i-b, ii-c, iii-a, iv-d$
• D
  $i-a, ii-b, iii-d, iv-c$