A mutant version of mouse-ear cress (Arabidopsis thaliana) has been engineered to convert it from a long-day plant to a short-day plant. What is responsible for triggering the development of flowers in this plant?

Day length decreases back to a critical length, causing an appropriate decrease in Pr : Pfr ratio and increased expression of genes required for flowering.

Day length increases to a critical length, causing an appropriate increase in Pfr : Pr ratio and increased expression of genes required for flowering.

Day length decreases back to a critical length, causing an appropriate decrease in Pfr : Pr ratio and increased expression of genes required for flowering.

Day length increases to a critical length, causing an appropriate increase in Pr : Pfr ratio and increased expression of genes required for flowering

Long Day Plants- The plants which flower when the day length is longer than the critical day length(Plants physiological events such as seed germination, initiation of flowering, asexual reproduction are triggered by a photo-period of specific length, this specific period length is critical day length). Examples- Spinach, wheat and spring barley.

Short Day Plants- The plants which flower when the day length is less than the critical day length. Examples- Soybean and tobacco.

So, In short day plants a flash of red light (Pr) during dark period prevents flowering, and the effect is reversed by the flash of far-red light (Pfr). In case of long day plants a flash of red light (Pr) during night break promotes flowering and a flash of far-red light (Pfr) during dark period prevents flowering.

hence option c.