Combinatorial control of gene expression a. involves every gene using a different combination of transcriptional regulators for its proper expression. b. is seen only when genes are arranged in operons. c. involves only the use of gene activators that together regulate genes appropriately. d. involves groups of transcription regulators working together to determine the expression of a gene.

The true statement will be - D

It is a involvement of groups of transcriptional regulators which work together to determine the  expression of a gene.

Explanation:

Combinatorial gene regulation is a mechanism by which small numbers or groups of transcriptional factors or regulators can control the expression of a much larger gene with temporal and spatial patterns.

The process by which a cell regulates the conversion of DNA to RNA to increase gene activity is known as Transcriptional regulation. A single gene can be regulated by altering the RNA which is transcribed.

The gene control allows the cell to respond to a variety of intracellular and extracellular signals.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added