What do '$a$' and '$b$' represent in the given structure?

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Disaccharide	$(i)$ Unsaturated fatty acid
$(B)$ Galactose	$(ii)$ Saturated fatty acid
$(C)$ Oleic acid	$(iii)$ Monosaccharide
$(D)$ Stearic acid	$(iv)$ Monosaccharide pair

Categorize the following processes as Anabolic or Catabolic:
$I -$ Protein synthesis,
$II -$ Lactic acid fermentation,
$III -$ Aerobic respiration,
$IV -$ Alcoholic fermentation,
$V -$ Synthesis of cholesterol from acetic acid,
$VI -$ Photosynthesis,
$VII -$ Digestion,
Identify the Anabolic and Catabolic processes respectively.

$A$: Dextrins are intermediate polysaccharides formed during the hydrolysis of starch into sugar.
$R$: Ascorbic acid is a sugar derivative.

The energy currency of the cell is ......... .

The energy stored in the form of chemical bonds is called $ATP$.