  We investigate dust attenuation and its dependence on viewing angle for 308
star-forming galaxies at $1.3\leq z\leq2.6$ from the MOSFIRE Deep Evolution
Field (MOSDEF) survey. We divide galaxies with a detected H$\alpha$ emission
line and coverage of H$\beta$ into eight groups by stellar mass, star formation
rate (SFR), and inclination (i.e., axis ratio), then stack their spectra. From
each stack, we measure Balmer decrement and gas-phase metallicity, then we
compute median \AV and UV continuum spectral slope ($\beta$). First, we find
that none of the dust properties (Balmer decrement, \AV, $\beta$) vary with
axis ratio. Second, both stellar and nebular attenuation increase with
increasing galaxy mass, showing little residual dependence on SFR or
metallicity. Third, nebular emission is more attenuated than stellar emission,
and this difference grows even larger at higher galaxy masses and SFRs. Based
on these results, we propose a three-component dust model where attenuation
predominantly occurs in star-forming regions and large, dusty star-forming
clumps, with minimal attenuation in the diffuse ISM. In this model, nebular
attenuation primarily originates in clumps, while stellar attenuation is
dominated by star-forming regions. Clumps become larger and more common with
increasing galaxy mass, creating the above mass trends. Finally, we argue that
a fixed metal yield naturally leads to mass regulating dust attenuation. Infall
of low-metallicity gas increases SFR and lowers metallicity, but leaves dust
column density mostly unchanged. We quantify this idea using the
Kennicutt-Schmidt and fundamental metallicity relations, showing that galaxy
mass is indeed the primary driver of dust attenuation.
