Reasons of it are / The reasons of it are ?

[nkspbrus]

Hello everybody. I am confused by the usage of a definite article, esp. with plurals.
What are the differences among these sentences and which are grammatically correct?

1) Reasons of this are unemployment and poverty.
2) The reasons of it are unemployment and poverty.

(The?) Other examples:

1) Here are good ways to do it: ...
2) Here are the good ways to do it: ....

When we have a verb "to be" after plural or some prepositional clauses like the one with "of", does it mean that that plural noun is specific and we strictly have to use "the"?
Or in any cases we can use no definite article, by this we express that these are just "some of reasons" and "some of good ways" and not the complete list, or just like we say it in a general way not wanting to make it "too" precise.

I hope I got my point clearly. I would be glad for any help as I tried to figure this all out on the internet but couldn't. Thanks.

[Alan]

For general points such as use of articles, please refer to the ESL Learning Centre.

N.B. Reason FOR, not 'of'.