= Solution
A K-star-like integrated spectrum indicates that old or intermediate-age cool <stars>, often luminous <red giants>, dominate the observed optical/near-infrared light. It suggests little ongoing formation of very luminous hot O and B <stars>. It does not imply that every <star> is K type: faint low-mass dwarfs and remnants can contribute substantial <mass> while contributing little light.
Using the reference wavelength printed in the problem,
$$
\boxed{z=\frac{874.0-854.4}{854.4}=0.02294.}
$$
The low-redshift Hubble estimate is
$$
\boxed{D\simeq\frac{cz}{H_0}\simeq96.9\,\mathrm{Mpc}.}
$$
<Peculiar velocities> and the distinction between <luminosity> and angular-diameter distance introduce percent-level or larger corrections to this simple estimate. The numerical result intentionally uses the supplied calcium reference rather than replacing it with a different tabulated line wavelength.
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