By the same techniques used for genetically enhancing plants, making them disease- or pest-resistant, researchers have been able to increase the amount of protein in potatoes, sweet potatoes, and tobacco.
(a) by the same techniques used for genetically enhancing plants, making them
(b) with the same techniques to genetically enhance plants, so that they are
(c) employing the same techniques used to genetically enhance plants so that they are
(d) employing the same techniques to genetically enhance plants, which makes them
(e) employing the same techniques for genetically enhancing plants that make them

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.

maybe because its impossible for balloons to lift a whole entire house.

straight probes are used primarily for measuring flow as it is approaching the test area. its geometry allows the probe to be mounted so that it is in the direct line of airflow.