Answer:
A cold front is defined as the transition zone where a cold air mass is replacing a warmer air mass. Cold fronts generally move from northwest to southeast. The air behind a cold front is noticeably colder and drier than the air ahead of it.
The best meaning of converge as it is used in the following sentence would be "come together" which is not only the best in this sentence but best in general.
D They establish a rough untamed setting