Carbonate reactions

This task is about  setting up a fair test.
Stacey wanted to find out whether calcium carbonate or sodium carbonate reacted faster with vinegar. Using the apparatus shown, she decided to do this by observing how long it took for the carbon dioxide released to turn lime water milky.
carbonate reactions experiment
 
Tick whether or not Stacey must include each step to make this a "fair" test.

Question

a)  Same amounts of calcium carbonate and sodium carbonate.

    • Yes

    • No

Question

b)  Identical test tubes for the reaction.

    • Yes

    • No

Question

c)  Trials must be carried out at exactly the same time.

    • Yes

    • No

Question

d)  Vinegar used should be of same type and amount.

    • Yes

    • No

Question

e)  Solid should be stirred thoroughly with the vinegar.

    • Yes

    • No