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A
Pressure stays the same
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B
Pressure decreases
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C
Pressure increases approximately 10 times — water pressure increases by roughly 1 atmosphere (14.7 psi) for every 10 metres of depth
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D
Pressure only changes if the submarine moves quickly
Why this is the answer
HYDROSTATIC PRESSURE: Water pressure increases with depth because of the weight of water above. RULE OF THUMB: Pressure increases by approximately 1 atmosphere (atm) or 14.7 psi for every 10 metres (33 feet) of seawater depth. At the surface: 1 atm (atmospheric pressure). At 10 m: 2 atm total. At 100 m: ~11 atm total. At 100 m, the submarine's hull experiences approximately 10× the pressure compared to the surface. Deep ocean trenches (10,000 m+) have pressures exceeding 1,000 atm. This is why submarines have thick pressure hulls and why scuba divers must manage nitrogen narcosis and decompression at depth.
Source: ASVAB MC, Fluid Pressure — Hydrostatic Pressure