**Core Concept**
Case-control studies are a type of observational research design used to investigate the association between a particular exposure and a disease or outcome. They are particularly useful for studying rare diseases or outcomes where cohort studies may be impractical.

**Why the Correct Answer is Right**
Case-control studies are often less expensive and time-consuming compared to cohort studies, as they do not require long-term follow-up of large cohorts of participants. Additionally, case-control studies can be used to study multiple diseases simultaneously, making them a cost-effective option for investigating rare or multiple outcomes. However, they are not inherently less prone to bias, and in fact, they can be susceptible to various biases, including selection bias and recall bias.

**Why Each Wrong Option is Incorrect**
**Option A:** "Cheaper" is a correct advantage of case-control studies, as they often require less resources compared to cohort studies.
**Option B:** "Less time consuming" is also a correct advantage of case-control studies, as they typically require shorter study periods compared to cohort studies.
**Option C:** "Possible to study many diseases" is a correct advantage of case-control studies, as they can be used to investigate multiple outcomes simultaneously.
**Option D:** "Less chances of bias" is incorrect, as case-control studies can be susceptible to various biases, including selection bias and recall bias.

**Clinical Pearl / High-Yield Fact**
When designing a case-control study, it's essential to carefully select the control group to minimize selection bias. This can be achieved by using hospitalized controls or community controls, depending on the study's research question and target population.

**Correct Answer: D. Less chances of bias**