A

To match the columns correctly, we need to determine the final temperature of the mixtures described in column II based on the given initial conditions in column I.

Step 1: For (i) 0ºC ≤ Tmix < 10ºC:
When mixing 10 gm of water at 90ºC with 5 gm of water at 0ºC, the final temperature Tmix can be calculated using the formula for thermal equilibrium:
$$ m_1 c (T_1 - T_{mix}) = -m_2 c (T_2 - T_{mix}) $$
where m1 is mass of hot water, m2 is mass of cold water, T1 is the temperature of hot water, and T2 is the temperature of cold water. This leads us to a Tmix below 10ºC because of excess cold water. So, this matches to [A].

Step 2: For (ii) Tmix ≤ 100ºC:
1 gm of steam at 100ºC mixed with 6 gm of ice at 0ºC will cause the ice to melt and then some of the resulting water will be heated. This mixture could potentially give us a Tmix value in the range up to 100ºC, making it match [B].

Step 3: For (iii) 20ºC ≤ Tmix < 30ºC:
Mixing 100 gm water at 10ºC with 3 gm steam at 100ºC will increase the temperature of the cold water significantly but not to boiling, indicating a final temperature in this range. Hence, it aligns with [C].

Step 4: For (iv) 30ºC ≤ Tmix:
Combining 5 gm of water at 70ºC with 5 gm of ice at 0ºC will yield a mixture hot enough to end up with temperatures above 30ºC, correlating with [D].
Based on these detailed evaluations, the final matches are: (i):[A], (ii):[B], (iii):[C], (iv):[D].
Therefore, A.