Alternately called typhoons, hurricanes, and tropical depressions, met

What we need to realize here first is that this is a classic Modifier question. Once you have that down, the key to solving it is to understand that the dependent clause beginning with ‘Alternately’ contains a list.

Now, you need to figure out two things:
1. What is the subject that should be modified
2. Is the right subject being modified

In the sentence, the subject is ‘cyclones’ which does not come after the dependent clause.
Based on this we can now look at the options

A – Alternately called A, B, and C, meteorologists generally… Eliminate
E – Wrong subject is modified … Eliminate

Now, let’s look at B, C, and D

B – wrong verb form is used … Eliminate
C – the issue with the verb remains. Plus, there is a change in the intended meaning: this option suggests that meteorologists recognized only six different factors … Eliminate
D – This is the correct answer. The subject comes after the modifier and the correct verb form ‘are formed’ is used.

Hope this helps!