According to the ABCDE model of flower development, different combinations of MADS box proteins belonging to class A, B, C, D, and E bind to each other to form a tetrameric structure referred to as "floral quartet" as given below. The floral quartet bind to DNA to activate transcription of the genes needed to specify each floral organ types.AP1 = APETALA 1, AP3 = APETALA 3, PI = PISTILLATA, AG = AGAMOUS, STK = SEEDSTICK, SHP = SHATTERPROOF, SEP = SEPALLATA 1/2/3Which one of the following options represents the combination of floral quartets that specify petals and carpel whorl of the flower, respectively?

Correct option is A

Detailed Explanation:

Let's review the floral quartets and their roles:

Petals: Petals are formed by the expression of APETALA 1 (AP1) and APETALA 3 (AP3). These genes, part of the A and B classes, specify the formation of the petal whorl.
Carpels: The formation of the carpel whorl is controlled by AGAMOUS (AG), a gene in the C class, which is crucial for carpel development.

Option B: AP1, AP3, SEP, PI
- This combination includes AP1 and AP3, which are both involved in the formation of petals. It also includes SEP (SEPALLATA), which is a gene involved in the overall formation of the flower. While PI is related to pistils, the combination of AP1 and AP3 in this option focuses on petals.
Option E: AG, SEP, SEP, SEP
- AG (AGAMOUS) is key for the formation of carpels, and the presence of SEP indicates that the overall flower structure is maintained. This combination is essential for carpel development.

Option 2 (C and D): Incorrect because C and D do not correctly represent the combination of petals and carpels.
Option 3 (A and B): Incorrect because A (AP1, AP1) and B (AP3, SEP, SEP, SEP) are not the best fit for the correct combination of whorls.
Option 4 (D and E): Incorrect because D is not focused on petals and E only addresses carpels.