Question

read this paragraph from a passage.
a genetically modified organism is one whose genes have been altered. genes from one species are inserted into a second species. the goal of this process is to introduce a desired trait or characteristic into the second species. for example, corn is vulnerable to certain kinds of worms that eat and destroy the corn stalks. genes can be taken from some bacteria and inserted into the corn. these genes from the bacteria enable the corn to produce proteins that kill the worms. this genetically modified corn is now resistant to these pests. other plants, such as tomatoes, have been genetically altered in a similar fashion, to remain fresher longer.
what is the topic sentence of this paragraph?
a genetically modified organism is one whose genes have been altered.
for example, corn is vulnerable to certain kinds of worms that eat and destroy the corn stalks.
genes from one species are inserted into a second species.
the goal of this process is to introduce a desired trait or characteristic into the second species.

Explanation:

A topic sentence introduces the main idea of a paragraph. Here, the paragraph is about genetically - modified organisms (GMOs). The first sentence defines what a GMO is, which sets the stage for the rest of the paragraph. The other sentences provide details (like how genes are transferred, examples of GMOs) that support the definition in the first sentence.

Answer:

A. A genetically modified organism is one whose genes have been altered.