Triangulation is a trustworthy method of measuring stellar distances regardless of the distance. a. true b. false

Once we've measured a star's parallax, triangulation is
the math we use to determine the star's distance.

You ask whether it's a "trustworthy" method.

For stars close to us, it's the only method we have.
So within some maximum distance, it's the most trustworthy method
available, (and also the least trustworthy).
The accuracy of the triangulation only depends on the accuracy of
the parallax measurement ... and RIGHT THERE is the problem.

The parallax of a star is always a tiny angle.  The parallax of the
NEAREST star outside the solar system is 0.769 of a second.
That's 0.000217 of a degree ( ! ), and as you get farther away,
the parallax gets SMALLER.  When you reach for stars past
some certain distance, their parallax becomes so small that
we can't measure it any more.

So I guess the answer to this question is "False", because it says
"... regardless of the distance.". 

Alkaline earth metals are found in group 2 of the periodic table.