Final answer:
The client should take the iron with a full glass of water. Taking iron with milk or a calcium supplement can decrease absorption, while taking it on an empty stomach can cause gastrointestinal side effects.
Step-by-step explanation:
The client should take the iron with a full glass of water. This statement indicates understanding because iron should be taken with water for optimal absorption. Taking the iron with milk (option a) or with a calcium supplement (option d) can decrease iron absorption because calcium inhibits iron absorption. Additionally, taking iron on an empty stomach (option c) may cause gastrointestinal side effects, so it is generally recommended to take iron with food.