पर्यावरण अध्ययन पर आधारित क्रियात्मक अनुसंधान (active research) के किस चरण में परिकल्पना (hypothesis) का निर्माण किया जाता है?

Prolonged occupational exposure to excessive noise from heavy machinery without hearing protection causes noise-induced hearing loss. Excess noise is categorized as a:

Long-term exposure to indoor air pollutants, such as smoke from burning biomass fuels, significantly increases the risk of developing chronic respiratory conditions like: