Explanation:

When passing through a railway line and noticing that two trains from opposite directions are running on the same line, it is important to take immediate action to prevent any potential accidents or collisions. The correct answer in this scenario is option 'B', which is to rush to either of the engine staff and inform them about the situation. Let's understand why this is the best course of action:

1. Ensuring Safety:
The primary concern in this situation is the safety of the passengers on both trains as well as other individuals who may be present in the vicinity. By immediately informing the engine staff, they can take necessary steps to avert any accidents or collisions and ensure the safety of everyone involved.

2. Professional Expertise:
The engine staff consists of trained professionals who are responsible for operating and controlling the trains. They are well-equipped to handle such situations and have the knowledge and experience to make quick decisions to avoid any mishaps. By informing them, you are alerting individuals who can take appropriate action based on their expertise.

3. Communication Channel:
The engine staff is the closest point of contact for immediate communication with the trains. They can immediately relay the information to the respective train drivers and take necessary steps to ensure the safe passage of both trains. By rushing to them, you are utilizing the most direct and effective communication channel available in this situation.

4. Time-sensitive Issue:
In a scenario where two trains are running on the same line, time becomes a critical factor. Waiting and seeing until the trains pass on (option 'D') may not be the best choice as it can lead to a delay in taking action and potentially increase the risk of accidents. By rushing to the engine staff (option 'B'), you are taking immediate action and minimizing the time gap between noticing the situation and informing the relevant authorities.

In conclusion, when passing through a railway line and encountering two trains from opposite directions running on the same line, it is crucial to choose the correct course of action. Rushing to either of the engine staff and informing them (option 'B') is the best choice as it ensures safety, utilizes professional expertise, utilizes the most direct communication channel, and minimizes the time gap in taking necessary action.