No, this answer is not correct. Officially all countries have to open up their economies. How ever market liberalization took the smallest progress in the only sectors (the agriculture and textile sector) were less developed countries might have profited from more open market access.
At the same time less develop countries had to open their markets in fields were they could not compete with transnational concerns (TNCs), preventing them from developing an own industry in these fields in the future
No points
If you didn't read the answer carefully enough and you were thinking of the extended time period for implementation, sometimes grated to less developed countries (like e.g. with the TRIPs agreement) you might get
0.1 points ;-)