Prokaryotes and eukaryotes share some mechanisms for controlling gene expression, but all of the following are uniquely used in eukaryotes except:
a. operons for coordinated gene expression
b. chromatin remodeling
c. rna processing
d. enhancers, silencers, cell-type specific factors

The correct answer is a. Operons for coordinated gene expression

Explanation:

Operons are normally found in prokaryotes and are absent in most of the eukaryotes. Operons are the sets of genes which is transcribed and expressed as a unit. An operon has a promoter, an operator and some structural genes. The operator regulated the transcription and expression of operon thereby regulating the gene expression in bacteria.

So multiple genes are transcribed as a unit which is present in an operon for example lac operon. In lack operon, three structural genes are present that code for different enzymes and are transcribed together.

In eukaryotes, one transcription unit contains only one gene so they are monocistronic therefore operon model is normally not used by eukaryotes to regulate gene expression.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.