18) A
Since volume of water is rounded to nearest 10 cm^3,
Minimum volume of water = 5
1% of 5 = 0.05
Since volume of each droplet is 0.02 rounded to the nearest 0.01, maximum volume of droplets = 0.025
To ensure we do not have more than 1%, we would need = 0.05 / 0.025 = 2 droplets