Final answer:
The process of synthesizing an mRNA strand from a DNA strand within the nucleus is called transcription, which is the correct answer a) to the student's question.
Step-by-step explanation:
The synthesis of mRNA from a DNA strand in the nucleus is known as transcription. This is the first step of protein synthesis. During transcription, an enzyme called RNA Polymerase unwinds the DNA and synthesizes a strand of mRNA using one of the DNA strands as a template. The newly formed mRNA strand is complementary to the DNA template strand, except that uracil (U) is used in the place of thymine (T) when pairing with adenine (A). This mRNA then carries the genetic information from the nucleus to the cytoplasm where it is used in the next step of protein synthesis, known as translation. The correct answer to the student's question is a) Transcription.
Transcription is not only responsible for the creation of mRNA but also for transfer RNA (tRNA) and ribosomal RNA (rRNA), which are both necessary for protein synthesis. The process is selective, with only specific genes or groups of related genes being transcribed at any given time.