got it,I haven't checked the artical more carefully 
To your question:Q4: (10-13)
The findings of the study mentioned in line 27, if valid for rain-forest regions in general,
suggest that which of the following is an obstacle most likely to be faced by those
wishing to promote rain-forest preservation by implementing the proposal mentioned in
line 1?
A. Lack of legal property rights tends to discourage local farmers from investing the
time and resources required to successfully implement new agricultural
technologies.
B. The ability to evaluate the wider economic ramifications of adopting new
aricultural technologies depends on a relatively high level of formal education.
C. Isolation from the market economy tends to restrict local farmers’ access to new
agricultural technologies that could help them to increase their productivity.
D. Ready availability of uncultivated land tends to decrease local farmers’ incentive
to adopt new agricultural technologies that would reduce their need to clear new
land for cultivation.
E. Traditions of self-sufficiency and reliance on kinship ties tend to diminish local
farmers’ receptivity to new agricultural technologies introduced by people from
outside the local community.
Answer
------------------------------------------------------------------------------------------------------------ we are told in line 41-45: " but availability of uncultivated land reduced the incentive to employ the productivity-enhancing tech-nologies" and in line 4-11 we are told : "new agricultural technolo- gies, such as improved plant varieties and use of chemical herbicides, which would increase productivity and slow deforestation by reducing demand for new cropland." so choice D is right | 
