Answer:
Correct option is
Part 1: millimeter --->> centimeter
Part 2: milligram --->> centigram
Explanation:
Part 1: Given the conversion i.e
A. millimeter --->> centimeter
B. kilometer --->> meter
C. centimeter --->> millimeter
D. meter --->> millimeter
we have to find that convert which requires division.
As from the above conversions only in the first option the unit in LHS is smaller than RHS i.e unit millimeter is smaller than centimeter i.e
A.

B.
C.
D.

Option A is correct i.e Option A requires division
Part 2: Given the conversion i.e
A. milligram --->> centigram
B. kilogram --->> gram
C. centigram --->> milligram
D. gram --->> milligram
we have to find that convert which requires division.
As from the above conversions only in the first option the unit in LHS is smaller than RHS i.e unit milligram is smaller than centimeter i.e
A.

B.
C.
D.

Option A is correct i.e Option A requires division