C.

Petunia

Floral formula is of Solanaceae family, i.e. of Petunia, while Brassica is form Brassicaceae whereas, Allium belongs to Liliaceae and Sesbania is from Fabaceae family.
As characteristic features of Solanaceae are
(i) Inflorescence - Cymose
(ii) Flower - Ebracteate, actinomorphic, bisexual, pedicellate. 
(iii) Calyx - Sepals 5, gamosepalous, valvate aestivation. 
(iv) Corolla - Petals 5, twisted or valvate aestivation
(v) Androecium - Stamens 5, epipetalous. 
(vi) Gynoecium - Bicarpellary, syncarpous, axile placentation, superior ovary and bilocular, which is represented as floral formula.

C.

syconus

Syconus fruit develops from the hypanthodium inflorescence, eg, Ficus carica, F. religiosa, F. benghalensis. The flask-shaped receptacle encloses female flowers that give rise to achene-like fruitless. This fruit possesses a small pore protected by scaly leaves. The receptacle that becomes fleshy is edible.

C.

Fifteen

Pulm, rose are perigynous and guava, cucumber are epigynous. So, total remaining plants are hypogynous.

B.

Six

A superior ovary is an ovary attached to the receptacle above the attachment of other floral parts. In this case the flower is said to be hypogynous.e.g., China, rose, mustard, brinjal, potato, onion and tulip. Guava and cucumber have inferior ovaries or epigynous flowers. 
So, out of 8 given names, 6 have superior ovaries. 

B.

Multi carpellary apocarpus gynoecium

Aggregate fruits of etecrio are those fruits that develop from the merger of multiccarpelllary apocarpus gynoecium ( ovary). In contrast, a simple fruit develops from one ovary, Aggregate fruit may also be called accessory fruits in which part of the flower and form part of the fruit, e,g., raspberry, etc.