Option 1 states that arsenic present in groundwater can be partially removed along with iron by precipitation/coagulation method if iron is also present in the water. This means that if both arsenic and iron are present in the water, they can be removed to some extent using a process called precipitation or coagulation. Precipitation involves adding a chemical agent to the water that causes the arsenic and iron particles to clump together and settle out. Coagulation refers to the process of allowing the clumped particles to form larger flocs that can be easily separated from the water.

Option 2 suggests that arsenic can be removed by boiling the water, even if iron is absent. However, this statement is not correct as boiling water does not effectively remove arsenic.

Option 3 claims that arsenic can be removed through UV treatment. While UV treatment can disinfect water by killing bacteria and viruses, it is not effective in removing arsenic.

Option 4 states that filtration can remove arsenic, even if iron is absent. Filtration is a commonly used method to remove impurities from water, but it is not effective in removing arsenic.

Therefore, the correct answer is option 1, stating that arsenic can be partially removed along with iron by