How many valves does the modern trumpet have?
3
4
6
only 1
Modern trumpets have most a three (or, infrequently, four) piston valves, each of which increases the length of tubing when engaged, thereby lowering the pitch. The first valve lowers the instrument's pitch by a whole step  the second valve by a half step , and the third valve by one and a half steps. 
reach: rather globalmusicmusical instruments
Answers by country
3
4
6
only 1
answers
 Greece
Greece12
 Australia
Australia19
 the Netherlands
the Netherlands14
 the United States
the United States104
 Germany
Germany41
 Poland
Poland1584
 the United Kingdom
the United Kingdom46
 Indonesia
Indonesia62
 India
India16
 Republic of Ireland
Republic of Ireland10