The wide diversity of arthropod body plans can be attributed to:

A. specific coordination between embryonic cells through plasmodesmata
B. mutations in genes that regulate the development of limbs, mouthparts, wings, etc.
C. flexibility in metabolism that lets them use a variety of carbon and energy sources
D. acquisition of mitochondria through endosymbiosis of proteobacteria

Option B.

Mutations of genes that regulate the development of limbs, mouthparts,wings e.t.c.

Explanation:

Arthropoda are the largest group of invertebrates. They have exoskeleton, jointed appendages and segmented bodies. They are characterized by jointed limbs and curticle made up of chitin. They are bilaterally symmetrical and have external skeleton. Their body plans is so diverse and are found in all environment. Change in genetic composition has lead to development of diverse body plans like wings, jointed limbs, segmented bodies e.t.c. examples are insects, crustaceans, myriapods e.t.c.

your answer is "the 1950's"

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.