Question

a chemical from outside a cell that promotes cell division is called a
growth factor.
nutrient.
telomere.
promoter.
mutagen.

Explanation:

• A growth factor is a chemical (usually a protein) from outside a cell that stimulates cell division and growth.
• A nutrient is a substance needed for growth, metabolism, etc., but not specifically for promoting cell division in this context.
• A telomere is a region at the end of a chromosome, not a chemical promoting cell division.
• A promoter is a DNA sequence (in genetics) or a substance that initiates transcription or a chemical reaction, not related to cell division promotion from outside the cell.
• A mutagen is a substance that causes mutations, not cell division promotion.

Answer:

A. growth factor.