The answer to your question is A. Wrought iron because amongst its other properties, wrought iron becomes soft at red heat, and can be easily be forged and forge welded.
Answer : The reagent present in excess and remains unreacted is, 
Solution : Given,
Moles of 
= 3.00 mole
Moles of = 2.00 mole
Excess reagent : It is defined as the reactants not completely used up in the reaction.
Limiting reagent : It is defined as the reactants completely used up in the reaction.
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,
From the balanced reaction we conclude that
As, 2 moles of react with 1 mole of
So, 3.00 moles of react with 
moles of
From this we conclude that, is an excess reagent because the given moles are greater than the required moles and is a limiting reagent and it limits the formation of product.
Hence, the reagent present in excess and remains unreacted is,
"Lipids<span> are like </span>carbohydrates<span> in way that the true fats contain only carbon, hydrogen, and oxygen. Both </span>carbohydrates and lipids<span> act as the main fuels and energy storage compounds of the human body. They are also called SACCHARIDES and grouped as: Monosaccharides, Disaccharides, Trisaccharides, Polysaccharides."
Source credit: </span>https://www.quora.com/What-are-the-differences-and-similarities-between-carbohydrates-and-lipids
Frequency = speed of light/ wavelength of photon. wavelength = speed of light/frequency = 3 x 10^8 / 2.43 x 10^8= 1.23m
