Question

1. nuclear fusion has not yet been harnessed as an energy source because ______.\

\bigcirc the energy is hard to control\
\bigcirc lasers are too dangerous\
\bigcirc of a lack of deuterium\
\bigcirc sufficient pressure cannot be generated

Explanation:

Nuclear fusion requires extremely high pressure (and temperature) to overcome the electrostatic repulsion between atomic nuclei. Current technology cannot sustain the necessary pressure for continuous, net-energy-positive fusion as a viable energy source. Deuterium is abundant in water, lasers are a tool (not the core barrier), and fusion energy's core challenge is the extreme conditions needed, not inherent uncontrollability of energy output.

Answer:

○ sufficient pressure cannot be generated