Transgenic crops are those that have been genetically modified to possess a desired trait or characteristic by the introduction of genes from other organisms. The following techniques/phenomena are used in creating transgenic crops:

1. Budding and grafting in fruit plants: This is a traditional method of vegetative propagation, in which a scion (the desired plant part) is grafted onto a rootstock (a compatible plant) to create a new plant with the desired traits.

2. Cytoplasmic male sterility: This technique is used to create hybrid plants that are more productive than their parent plants. It involves the manipulation of the mitochondrial genome to induce male sterility, which forces the plants to cross-pollinate with other plants and produce higher yields.

3. Gene silencing: This technique is used to "turn off" the expression of certain genes, which can help to reduce unwanted traits or enhance desired traits. It involves the use of RNA interference (RNAi) or other methods to block the expression of specific genes.

Therefore, only options 2 and 3 are correct as they are used in creating transgenic crops.