The CST prepares a collagen sponge called

$q,$ by moistening it$.$

a$.$ Avitene

b$.$ Bicol

c$.$ Grafton

d$.$ None of the above

Why did the starting time of operatic performances change from the afternoon to the evening at the end of the $19$th century?

Because opera is more magical at night

To accomodate the schedules of its working class patrons

Because its wealthy patrons were often late to performances

Because singers' voices needed to rest as much as possible on performance days