Agar is an excellent solidifying agent for microbiological media because Select one: a. it is not degraded by most microorganisms. b. solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C. c. it is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C are correct. d. agar provides an excellent source of nutrition for a variety of different microorganisms.

The correct answer is C. It is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C are correct.

Explanation:

Agar is a substance derived from red algae mainly used as part of some foods and microbiology works. In microbiology, agar is an ideal substance due to its stability and low susceptibility to temperature. Indeed, agar will remain solid below 90° C and liquid below 45°.

Moreover, agar is used in microbiology because this substance cannot be degraded by most microorganisms. Due to this, it is commonly used as a culture medium that will preserve stable properties as it is not affected by the bacteria, and other organisms growing in it. According to this, the correct answer is C.

a physical change is being made.