Which of the following causes the jet stream?

high altitude clouds
low altitude clouds
differences in size between two air masses
differences in temperature between two air masses

A jet stream forms high in the upper troposphere between two air masses of very different temperature. The greater the temperature difference between the air masses, the faster the wind blows in the jet stream. 
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So "Differences in temperature between two air masses" is the answer

Predator plants or carnivorous plants are plants that trap and consume small animals, insects, protozoans etc. and derive their nutrients and energy from them. Some predator plants are - pitcher plants, Venus fly trap, round leaved sundew, common butterwort etc.

These plants have adapted themselves to grow in places where the soil is thin or poor in nutrients, so they take these nutrients from other sources.