Statement : The air and rail services have been severely disrupted due to thick fog in the northern part of the country. Courses of Action : I. The rail and air services should be temporarily suspended in the region. II. People should be advised to make their travel plan keeping in mind the probable disruption resulting in delay or cancellation of services. III. The government should immediately install modern machines which will enable it to guide the rail and air services even if the thick fog develops.

The correct answer is D. All follow.

The statement says that the air and rail services have been severely disrupted due to thick fog in the northern part of the country. This means that the services are not running smoothly and there is a high probability of delays or cancellations.

Course of action I says that the rail and air services should be temporarily suspended in the region. This is a logical course of action because it will help to prevent accidents and ensure the safety of passengers.

Course of action II says that people should be advised to make their travel plan keeping in mind the probable disruption resulting in delay or cancellation of services. This is also a logical course of action because it will help people to plan their travel accordingly and avoid inconvenience.

Course of action III says that the government should immediately install modern machines which will enable it to guide the rail and air services even if the thick fog develops. This is a long-term solution that will help to prevent disruptions in the future.

Therefore, all three courses of action are logical and should be taken.