= Solution
Infer the component <masses> and spins from the <gravitational wave> phasing, using the <chirp mass> together with <binary mass ratio> information. The paper's representative pairs have total <masses> $2.8$, $11.4$ and $20M_\odot$, and the more massive mergers terminate their inspirals at lower frequencies. A black-hole ringdown and its quasi-normal modes identify the final compact remnant, although both a neutron-star–black-hole merger and a sufficiently massive neutron-star pair can also leave a <black hole>.
Tidal deformability and any disruption cutoff provide a more direct signature of a <neutron star> than total <mass> alone. A disrupted <neutron star> may supply a <gamma-ray burst>, <kilonova> and afterglow; these help distinguish matter-containing mergers from a clean black-hole pair. Their absence does not establish a black-hole pair, because jets are beamed and ejecta may be faint or swallowed. Measured <gravitational wave> <masses> are redshifted detector-frame <masses>; association with a host can supply the <redshift> needed for source-frame <masses>. Classification should combine the waveform and any electromagnetic evidence, allowing for parameter degeneracies.
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