Question

according to most scientists, cold fusion
○ will not be a practical source of energy on earth.
○ would be a practical source of energy on earth if it were less expensive.
○ will be a practical source of energy on earth within the next few decades.
○ will always continue to be a practical source of energy on earth.

Explanation:

Cold fusion has been widely discredited in the scientific community due to lack of reproducible evidence of practical, sustained fusion at low temperatures. Most scientists conclude it won't be a practical energy source on Earth. The other options either assume feasibility (which isn't supported) or incorrect timelines/claims.

Answer:

A. will not be a practical source of energy on Earth.