Explanation:

- Photoperiodism: This is the physiological reaction of organisms to the length of day or night. It is crucial in determining flowering time in many plants based on the duration of light they receive.

- This is the correct answer.

- Photomechanics: Not a term related to plant flowering or biology. It's more aligned with the study of mechanical properties of materials in relation to light.

- Transpiration: This refers to the process of water movement through a plant and its evaporation from aerial parts like leaves, stems, and flowers. It does not relate to the effect of day and night lengths on flowering.

- Phytoperidism: This option seems like a misspelling or incorrect version of photoperiodism, and it isn’t recognized in plant biology related to flowering processes.

- None of the above: Incorrect, since photoperiodism is the accurate term.