No es un instrumento del mariachi.
a.
el piano
c.
el violín
b.
la guitarra
d.
el arpa

A: El piano

Explanation: Los pianos son muy grandes para que el mariachi los muevan

a.el piano.

Explanation:

The Mariachi Serenades are associated with Mexican culture. Apart from the traditional guitars, these also tend to play the trumpet, violins ,among others. Usually there is a predominance of stringed instruments but the air ones were also incorporated over time. The piano is too big and heavy to serenade. This is one of the reasons why they don't use it.

well, i am responding 3 minutes into you posting. i assume 3 minutes?