Which of these is not needed by living organisms? water
air
energy
gravity
space

Gravity.

Explanation:

Without air, living organisms would suffocate and die.

Without water, living organisms would dehydrate and die.

Without energy, living organisms would die instantly.

Without space, living organisms would be squished together and die.

The only logical answer left is gravity.

answer; ////increased water pollution; ///////////////////////

nucleus

would be most reasonable answer tbh