Polymerase chain reaction (PCR) is a method widely used in molecular biology to make many copies of a specific DNA segment. Using PCR, a single copy (or more) of a DNA sequence is exponentially amplified to generate thousands to millions of more copies of that particular DNA segment.

• The process of cloning starts with cleavage of foreign DNA by a restriction endonuclease enzyme. 
• The cleaved DNA is ligated to plasmid vector for its transformation into host cell. 
• The DNA is ligated by DNA ligase by formation of phosphodiester bonds.

Polyethylene glycol method is used for gene transfer without a vector. Introduction of DNA into plant cell without involvement of a biological agent and leading to stable transformation is known as direct gene transfer. There are various methods for direct gene transfer one of which is chemical method. Certain chemicals e.g. PEG polyethylene Glycol, polyvinyl alcohol and calcium phosphate enhance uptake of DNA by plant protoplast. PEG and calcium phosphate are thought to precipitate DNA onto outer surface of plasmalemma and precipitate is taken up by endocytosis.
So, correct option is option B.

PCR or polymerase chain reaction is technique employed for amplification of gene of interest. The image shows 3 steps of PCR cycle, namely denaturation, annealing, and extension. Part A represents step of denaturation, where dsDNA is divided into two ssDNA under high temperature. For denaturation to occur, an approximate temperature of 90-92${}^o$C is required.

• Restriction endonuclease enzyme is known as molecular scissor because a restriction enzyme recognizes and cuts DNA only at a particular sequence of nucleotides and producing smaller fragments. 
• Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid-protein complexes. There are DNA and RNA helicases are involved in unwinding of nucleic acids. 
• In molecular biology, DNA ligase is a specific type of enzyme that facilitates joining of DNA strands toger by catalyzing formation of a phosphodiester bond. 
• The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, building blocks of DNA. 

In a pilot plant, glass vessels are replaced by stainless steel vessels. They are called bioreactors.

Restriction endonucleases are enzymes that recognise specific sequences in DNA and cut DNA into fragments. The specific sites are 4-6 bp long and are called as restriction sites. Since se enzymes cut DNA molecules into small fragments, y are also known as chemical/molecular scissors. They differ from regular scissors as y do not cut DNA at random sites rar y recognise specific DNA sequences for which y have complementary "teeth" just like a jigsaw puzzle pieces. EcoRI is restriction endonuclease enzyme present in E. coli as a part of restriction modification system. The nucleic acid sequence of its restriction site is 5' GAATTC 3'. HindIII is type I restriction enzyme isolated from Haemophilus influenzae. It cuts DNA at (5') AAGCTT (3'). BamHI  is a type II restriction endonuclease isolated from Bacillus amyloliquefaciens. It recognizes short sequences of DNA (5' GGATCC 3') and specifically cleaves DNA at this site. Since, all se enzymes have specific restriction sites, y are chemical scissors.