Final answer:
A cryophile is capable of growth at 4°C. Cryophiles, also known as psychrophiles, thrive in cold environments and can grow at temperatures close to and below freezing point. They are different from thermophiles, which grow at much higher temperatures.
Step-by-step explanation:
An organism that is labeled a cryophile is capable of growth at 4°C. Cryophiles, also known as psychrophiles, are organisms, including certain bacteria, fungi, and protists, that thrive at low temperatures. These organisms often have an optimum growth temperature close to 15°C and can survive temperatures below freezing point. They have adapted to cold environments through modifications such as antifreeze compounds and altered membrane structures. Cryophiles differ from thermophiles, which are organisms that grow best at temperatures of 40°C or higher, often found in high-temperature environments like hot springs and hydrothermal vents.
The correct answer to the question is option 1) growth at 4°C. This is because cryophiles are adapted to cold environments and could experience optimal growth at such low temperatures. Options involving hydrothermal vents, synthesizing liquid nitrogen, and producing liquid hydrogen do not apply to cryophiles, as those are characteristics associated with different types of organisms or technological processes. Therefore, neither choices C and D, nor option 2 is correct.