The correct answer is mRNA.
mRNA or messenger RNA is synthesized during the process of transcription, from DNA molecule which is used as a template. mRNA contains information about protein synthesis (translation) in the form of nucleotide triplets or codons.
In the example above: reference book is DNA molecule (template for copies), copies are mRNA, wood is amino acids (building blocks) and doghouse is protein.
Explanation: If the rate of photosynthesis increases, then the number of bubbles will increase.
