Question

### Solar Coronal Heating

The temperature of the solar corona (the Sun's outer atmosphere) is millions of kelvins ($\text{K}$), which is significantly hotter than the photosphere (the solar surface), which is only about $5,800\text{ K}$. Three hypotheses are proposed to explain how energy is transported from the photosphere and dissipated in the corona.

Wave Heating Hypothesis
Coronal heating is caused by magnetohydrodynamic (MHD) waves, specifically Alfvén waves. Convective motions of plasma in the photosphere continuously perturb magnetic field lines. This perturbation generates Alfvén waves that propagate upward along the magnetic field lines into the corona. The magnetic field acts as a waveguide, transporting this wave energy. Once in the corona, these waves undergo reflection and dissipation due to the low density of the coronal plasma, transferring their energy to the corona as thermal energy.

Nanoflare Hypothesis
Coronal heating is caused by magnetic reconnection. The convective motions of plasma in the photosphere twist and braid coronal magnetic field lines. This slowly stores magnetic energy in the coronal magnetic field. When the magnetic stress reaches a threshold, the magnetic field lines abruptly reconnect, releasing this stored magnetic energy in millions of localized, miniature explosions called "nanoflares." These nanoflares convert magnetic energy directly into thermal energy, heating the coronal plasma.

Turbulent Dissipation Hypothesis
Convective motions of plasma in the photosphere launch low-frequency magnetic waves. As these waves travel along the magnetic field lines into the corona, they interact with waves reflected from the boundaries of the corona. This interaction generates magnetohydrodynamic (MHD) turbulence. The turbulence cascades the energy to progressively smaller spatial scales. At very small scales, kinetic effects dissipate the turbulent energy, heating the corona.

Based on the three hypotheses, match each scientific statement about coronal heating to the specific category of agreement or uniqueness that describes it.