Why are scientists concerned about the use of the bt toxin, which is used to kill insects, in genetic engineering? a. the bt toxin is killing too many insects. b. the bt toxin stays in the soil for long periods of time. c. the bt toxin gene is not readily accepted by plants. d. the bt toxin has been known to cause disease in plants.

The right answer is C.

Bacillus thuringiensis (or Bt) is a Gram-positive bacterium that lives in the soil, and is commonly used as a biological alternative to the pesticide.

The Belgian company Plant Genetic Systems was the first company to develop genetically modified crops (tobacco) with insect tolerance by expressing cry genes from B.thuringiensis, the resulting crops contain delta-endotoxin.

The use of Bt toxins as plant-incorporated protectants prompted the need for extensive evaluation of their safety for use in foods and unintended potential in the environment.

c. establishing proper sleep hygiene

the planets have a circular orbit around the sun.