The fact that imprinting is most certain to occur if the opportunity for imprinting is presented to the organism at a very specific age indicates the existence of

a critical period

Explanation:

In developmental psychology and developmental biology, a critical period is a maturational stage in the lifespan of an organism during which the nervous system is especially sensitive to certain environmental stimuli(Wikipedia). It is a time during early postnatal life when the development and maturation of functional properties of the brain, its 'plasticity', is strongly dependent on experience or environmental influences(Sengpiel, 2007).

The fact that imprinting is most certain to occur if the opportunity for imprinting is presented to the organism at a very specific age indicates the existence of a critical period in the life of organisms.

Option A : the fern transitined from gametophyte generation to sporophyte generation.

The Parker probe.

Explaination:

for six years an artificial fertilizer is used on a apple orchard the orchard is next to a stream which empties in to a slat water bay during the last 5 years researchers have observed an increase in algae in the bay they have also sampled fish populations in the bay each year apex...

One parrot species that feeds on large seeds nests is in the same tree as a parakeet that feeds on small seeds, they occupy different niches.

Answer : 900 kg pumpkins

Need this store of protein: 

The seed consists of three components: embryo, endosperm (sometimes perisperm), and seed-coat. Both endosperm and embryo are the products of double fertilization, whereas the seed-coat develops from the maternal, ovular tissues. The seed habit is a significant advancement in the evolution of higher plants.

Anatomy of seed :-

Seed storage proteins provide a source of amino acids and reduced N necessary for germination and early growth of the seedling.

Consumers are dissatisfied with the way that large corporate  farms are treating nature's natural resources.

The nerves and muscles communicated with each other to trigger her reflexive response…

The processes of conduction, convection and radiation help distribute energy on earth...