Answer:
D
Explanation:
The cells are from different types of plants 
 
        
             
        
        
        
The answer should be 2 because planting trees gives out oxygen and we need oxygen to live
        
             
        
        
        
They create DNA molecules by assembling nucleotides. (Brainliest please) :)
        
             
        
        
        
Answer:
Option-D, a segment of DNA
Explanation:
A gene represents the particular segment of DNA which contains the instruction for the trait of an organism. The nucleotide sequence present in the segment provides the instruction in the form of codons.
The gene is present in the form of its alternative form called alleles which are located on the chromosomes at locus. The alleles represent the variants of the gene and therefore controls the two variety of a single trait.
Thus, Option-D is correct.