Couple (2 couple/couples of players)

Dear teachers,

In your opinion, I write:

a. 2 couple of players.

or: b. 2 couples of players.

c. Five married couple.

or: d. Five married couples.

What is the difference in meaning btw them?Is there a rule for “couple” with singular and plural form?

Thanks
Quoc

.
Couple is a regular countable noun with plural couples. Therefore, only B and D are correct.
.