What is the classical song played at beginning of x files episode trust no 1?

The classical song played at the beginning of the X-Files episode "Trust No 1" is "Adagio in G Minor" by Remo Giazotto.

This piece, also known as "Giazotto's Adagio," is actually a reconstruction of a supposed unfinished adagio by the famous composer Tomaso Albinoni. While Giazotto's work is popular and well-known, it is important to note that there is no evidence that Albinoni ever composed an adagio in G Minor.