Complementary, synthetic and random DNAs are used as,
A. Cloning vectors
B. Recombinant DNA
C. Transposons
D. Passenger DNA

Hint: DNA is a molecule composed of two polynucleotide chains that coil around one another to form a double-helix. The DNA acts as a passenger sometimes so that the genetic code can be transferred to the host organism.

Complete step by step answer: Passenger DNA is a piece of DNA that is isolated from the desired organism and inserted into a vector for cloning, where it combines with vector DNA. The passenger DNA contains the gene for desired traits to be introduced into the host organism. Passenger DNA can be complementary, synthetic and random DNAs. Passenger DNA combines with vector DNA to form recombinant DNA.
i. Cloning vector is defined as a small piece of DNA that can be stably maintained in an organism. Also, here the foreign DNA molecule is inserted for cloning.
ii. Transposons are the class of genetic elements that can be transmitted to different locations within a genome. Most of the transposons become inactive and do not move any longer.
iii Recombinant DNA is a biological technique in which the DNA from two organisms are joined together to form different traits. The recombinant DNA molecule is inserted into a host organism to produce new genetic combinations that are of value to science, medicine, agriculture, and industry.
Hence, the correct answer is option D.

Note: Passenger DNA which is also called Foreign DNA is a small piece of DNA that is taken from the desired organism and then inserted to the vector for cloning. The passenger DNA has a gene for desired traits to be visible in the host organism.