This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to use a cement mixer
Pour approximately 1 gallon (3.79 l) of water into the concrete mixer.
Be sure to use the correct amount of water per the cement mix instructions given by your specific mix label. If there is too much water added, the cement mix will come out too thin, become unmanageable, and not dry properly.

Choose your answer from:
[+] If there is not enough water, the mix will become too thick, it will not combine thoroughly, and will become unusable. Open the cement mix bag from the top and pour the entire contents into the cement mixer..
[+] A water-based cement mixer is ideal because it makes pouring concrete quicker and easier. If you have a liquid concrete mixer, you can also use water itself..
[+] Add a short amount of water gradually into the cement mix about 20 seconds before starting. Mix in about one inch at a time and keep working until the concrete is almost completely wet, adding more water as needed to accommodate..
[+] If you are unsure how much water to use, or if the label tells you how much cement to use, write down your ratios. Pump the mixture onto the concrete surface..
The answer is:
If there is not enough water, the mix will become too thick, it will not combine thoroughly, and will become unusable. Open the cement mix bag from the top and pour the entire contents into the cement mixer.