Each cell expresses, or turns on, only a fraction of its genes. the rest of the genes are repressed, or turned off. the process of turning genes on and off is known as gene regulation. gene regulation can occur at any point during gene expression, but most commonly occurs at the level of when the information in a gene's dna is transferred to mrna.

the correct answer is "transcription"

Explanation: Gene regulation is the process of activation and deactivation of genes. In the early stages of development, cells begin to assume specific functions. Gene regulation ensures that the affected genes are expressed at the appropriate times. Within the gene regulation factors are transcription factors, which are proteins that bind to DNA near the area where the gene is located, helping or inhibiting the transcription machinery. Other forms of regulation include epigenetic processes such as methylation, acetylation, phosphorylation, interference RNAs, among others. This entire regulatory network works together controlling the appropriate rates and times when genes are transcribed into mRNA.

it cools slower in the earth meaning the crystals have more time to form than lava on the surface