The correct answer is option 'A', a revolver.

Explanation:
The question asks about what the intruder had in his hand. To determine the answer, we need to analyze the given options and choose the most appropriate one. Let's examine each option:

a) Revolver: A revolver is a type of firearm that has a rotating cylinder with multiple chambers for bullets. It is commonly used for self-defense or criminal activities.

b) Knife: A knife is a sharp-edged tool used for cutting or stabbing. While it can also be used as a weapon, it is less likely to be the weapon of choice for an intruder compared to a firearm.

c) Iron rod: An iron rod is a long, solid piece of metal. While it can be used as a weapon, it is less common for an intruder to carry an iron rod compared to a firearm or a knife.

d) None of the above: This option implies that the intruder did not have any of the mentioned items in his hand. However, since the question specifically asks about what the intruder had in his hand, this option is not applicable.

Considering the given options, the most plausible choice for an intruder would be a revolver. A revolver is a widely used weapon and is often associated with criminal activities. It provides the intruder with means of intimidation and threat. The presence of a firearm in the hands of an intruder increases the potential danger and risk to the victims.

Therefore, based on the provided options and the context of the question, we can conclude that the intruder had a revolver in his hand.