Which of the following would require the use of recombinant DNA? 1. Crossing two apple trees to create better apples.
2. Breeding a donkey and a horse to make a mule.
3. Engineering bacteria that produce human insulin.
4. Creating a polyploid banana tree.

The answer is 3

For example, insulin is regularly produced by means of recombinant DNA within bacteria. A human insulin gene is introduced into a plasmid, which is then introduced to a bacterial cell. The bacteria will then use its cellular machinery to produce the protein insulin, which can be collected and distributed to patients

C- a hypothesis or d- an observation