Starch is converted into maltose with the help of a catalyst named:

The correct answer is Option (2) → Diastase

Enzymes are biochemical catalysts, each very specific in action. The enzyme diastase (present in malt) hydrolyses starch into maltose:

    2(C₆H₁₀O₅)_n + nH₂O → nC₁₂H₂₂O₁₁  (diastase)

NCERT (Pre-rationalised edition, 2022-23):
Conversion of Starch into Maltose – “The diastase enzyme converts starch into maltose.
2(C₆H₁₀O₅)_n(aq) + nH₂O(l) → nC₁₂H₂₂O₁₁(aq) (Diastase)”