Final answer:
The answer to the statement, "Railway crossing - stay stopped until the gate is fully raised," is a) True.
Step-by-step explanation:
The statement is a) true that one should remain stopped at a railway crossing until the gate is fully raised for safety. It is important for safety reasons to remain stationary and not proceed until the crossing gates are completely in the upright position and it is clear to cross. Moving forward before the gates are fully raised could put you in the path of an oncoming train that you may not see or hear until it's too late.
In regards to the other statements, number 14 implies waiting for a natural hazard (a swollen river) to subside which is a prudent and safe action akin to the railway crossing safety rule.
Regarding statement 16, it is False that high-voltage wires are wrapped in insulating material. They are, in fact, typically bare and are held aloft by insulating connectors to prevent the current from traveling down the towers.
For statement 18, the correct answer is False. The position vs time graph of an object that is speeding up will not be a straight line but rather a curve that steepens as the speed increases.