In a genetic engineering experiment, restriction enzymes can be used for:

Any DNA fragment

The answer to the question "In a genetic engineering experiment, restriction enzymes can be used for" is (c) any DNA fragment.

Restriction enzymes are specialized proteins that can cut DNA at specific recognition sites. These enzymes are used in genetic engineering to manipulate DNA fragments from various sources, including bacterial, viral, eukaryotic, or any other DNA. Their ability to recognize and cut specific DNA sequences allows scientists to isolate and manipulate specific genes or DNA regions for various purposes.

The choice (a), bacterial DNA only is incorrect because restriction enzymes can be used to cut DNA from any source.

The choice (b), viral DNA only is incorrect because restriction enzymes can be used to cut DNA from any source.

The choice (d), eukaryotic DNA only is incorrect because restriction enzymes can be used to cut DNA from any source.

Therefore, the correct answer is (c).