How do you find height of an object

I am making an app with C# and NGUI. In order to make the app work, I need to find which object is lower. How would you find that, in c#? This is my code:

using UnityEngine; using System.Collections;

public class NewQuestion : MonoBehaviour {

 public UILabel aText;

 public UILabel qText;

 public UISprite qaSet;

 public UILabel aButton;
 
 void Update() {
     
     Debug.Log ("aButton height: " + qText.height.ToString () + " position: " + qText.transform.position.y.ToString () + " Total: " + (qText.height + qText.transform.position.y).ToString ());
     Debug.Log ("aButton height: " + aButton.height.ToString () + " position: " + aButton.transform.position.y.ToString () + " Total: " + (aButton.height + aButton.transform.position.y).ToString ());
     Transform aTransform = aButton.transform;
     Transform qTransform = qText.transform;
     if ((qTransform.position.y + qText.height) <= (aTransform.position.y + aButton.height)) {
         qaSet.bottomAnchor.target = aTransform;
         qaSet.bottomAnchor.absolute = -32;
         qaSet.bottomAnchor.relative = 0f;
     } else {
         qaSet.bottomAnchor.target = qTransform;
         qaSet.bottomAnchor.absolute = -32;
         qaSet.bottomAnchor.relative = 0f;
     }
     qaSet.ResetAnchors();
     qaSet.UpdateAnchors();
 }

}

Thanks!

Edit:

What about how to change the height (this time the from-top-to-bottom height). For instance, how would I, in a script, change an object to be half the size of the room? What if I want to make it the same size as another object?