The following is an example of a variable interval schedule of reinforcement: A. For every 60 minutes that Jacob practices the violin, he earns $1 from his parents.
B. For every 3 songs Jacob practices on his violin, he earns $1 from his parents.
C. Jacob's parents place a dollar bill in his piggy bank when he practices his violin for an average of 8 songs.
D. Jacob's parents place a dollar bill in his piggy bank when he plays his violin for an average of 60 minutes each day.

dude you should crop your image so only the question shows. but   can you explain it better

i’m   sure probably just geuss and see which one you can get right, i’m pretty sure it is the combination of goods and services

the following men who did not in the unification of italy were.

a) giuseppe mazzini

c) alexander ll

the other two men were camilo cavour and giuseppe garibaldi they the unification of italy by yielding territories in the italian unification. in 1861 italy was declared a united-nation state under the sardinian king victor immanuel ll.