Final answer:
The experimental design used appears to be a randomized control trial with independent groups, since participants were randomly assigned to conditions, though additional information on how marital status influenced the assignment would be required to confirm if it's a matched-pairs design.
Step-by-step explanation:
The experimental design the researcher is using for Adam, Bob, Eric, and Jim appears to be a randomized control trial, which is a basic type of experimental design involving the random assignment of subjects into an experimental group and a control group.
The researcher's action of asking for marital status and then sending Bob and Jim to one condition and Adam and Eric to another suggests they are using this marital status information potentially as a way of pairing or matching subjects. However, since there's no explicit mention of marital status influencing the assignment to conditions, it's more likely that they are independent groups because participants were assigned at random to the groups.
If the researcher were to use marital status for matching, it would be a matched-pairs design, but the information given does not necessarily indicate that this is the case. It's important to note that for a truly randomized control trial, the researcher would ensure that the only difference between the experimental and control groups is the condition they are exposed to.