The most common form of legislative body in this region of the world is a one.

Unicameral one

Explanation:

 In the legislative, the unicameral is the system in which the laws are passed in more efficient way. In the government system, the unicameralism is system of having chamber of the legislative and the parliament.

 In the unicameral governing body, the incomparable law-production body of any place involves a solitary chamber or house, rather than a bicameral council.

It basically has two individual chamber from the law making body have a place with just one chambers and reserve an option to take an interest just in the chamber's procedures.

it sounds like either a or c