**Core Concept**
The question tests the concept of familial inheritance in malignancies, specifically focusing on cancers that have a known genetic predisposition. **Genetic syndromes** and **familial cancer syndromes** play a significant role in the development of certain types of cancer.

**Why the Correct Answer is Right**
Among the options provided, both **Ca breast (a)** and **Ca ovary (b)** are well-documented to have familial inheritance patterns, notably through **BRCA1** and **BRCA2** gene mutations. These genes are crucial for **DNA repair**, and mutations in them significantly increase the risk of developing breast and ovarian cancer.

**Why Each Wrong Option is Incorrect**
**Option C:** Ca testis does not have as strong of a familial inheritance pattern as breast or ovarian cancer, although some genetic factors may play a role.
**Option D:** Ca pancreas can have a familial component, especially in the context of **familial atypical multiple mole melanoma syndrome (FAMMM)** or **Peutz-Jeghers syndrome**, but it is less commonly associated with a direct familial inheritance pattern compared to breast and ovarian cancer.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that **BRCA1** and **BRCA2** mutations significantly increase the risk of both breast and ovarian cancer, making genetic screening and counseling important for families with a history of these cancers.

**Correct Answer:** a) Ca breast.