Interested in the Effects of Different Kinds of Instruction on Video

Multiple Choice

Interested in the effects of different kinds of instruction on video game performance, Martin asks 30 college freshmen to each play one hour of Ratchet and Klank..Participants are randomly assigned to one of three instruction groups: (1) complete the tasks as quickly as possible, (2) conserve as much health as possible find gold bolts (worth lots of money in equipment and ammunition) .Obviously, even in a single instruction group, not all players will obtain the same final score.These differences in an instruction group reflect:

A) between-groups variance.
B) within-groups variance.
C) effects of instruction.
D) effects of confounding variables.