In angiosperms, functional megaspore develops into
embryo sac
ovule
endosperm
pollen sac.
Embryo sac is also known as
Fertilization of egg takes place inside
Definations / Explanation :
$1.$ Nucellus
$2.$ Funicle
Choose the odd one w.r.t. gynoecium.
Polar nuclei are located in