Starting from the innermost part, the correct sequence of parts in an ovule is,
a. egg, nucellus, embryo sac, integument
b. egg, embryo sac, nucellus, integument
c. embryo sac, nucellus, integument, egg
d. egg, integument, embryo sac, nucellus.
The answer is the option (b) egg, embryo sac, nucellus, integument
The structure of an ovule reveals that the egg is located at the innermost part, followed by the embryo sac, which houses the egg apparatus. Next is the nucellus, which is enclosed by integuments.