  Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients can
appear when the source is in the low-hard and hard-intermediate states. The
spectral-timing evolution of the type-C QPO in MAXI J1535-571 has been recently
studied with Insight-HXMT. Here we fit simultaneously the time-averaged energy
spectrum, using a relativistic reflection model, and the fractional rms and
phase-lag spectra of the type-C QPOs, using a recently developed time-dependent
Comptonization model when the source was in the intermediate state. We show,
for the first time, that the time-dependent Comptonization model can
successfully explain the X-ray data up to 100 keV. We find that in the
hard-intermediate state the frequency of the type-C QPO decreases from 2.6 Hz
to 2.1 Hz, then increases to 3.3 Hz, and finally increases to ~ 9 Hz.
Simultaneously with this, the evolution of corona size and the feedback
fraction (the fraction of photons up-scattered in the corona that return to the
disc) indicates the change of the morphology of the corona. Comparing with
contemporaneous radio observations, this evolution suggests a possible
connection between the corona and the jet when the system is in the
hard-intermediate state and about to transit into the soft-intermediate state.
