**Core Concept**
The World Health Organization (WHO) and other global health authorities establish guidelines for safe levels of radioactivity in drinking water to protect public health from radiation exposure. Gross alpha (α) and beta (β) activities are key parameters used to assess the radioactivity of drinking water.

**Why the Correct Answer is Right**
Gross alpha activity refers to the total count of alpha particles emitted per liter of water, while gross beta activity refers to the total count of beta particles emitted per liter of water. The proposed guideline values for gross alpha activity in drinking water is 0.1 Bq/L, and for gross beta activity is 1.0 Bq/L. These values are intended to minimize the risk of radiation-induced health effects, such as cancer and genetic mutations, associated with long-term consumption of contaminated water.

The distinction between alpha and beta particles is crucial, as alpha particles are more easily absorbed by the body and have a shorter range, whereas beta particles can penetrate deeper into tissues and cause more damage. The guideline values are designed to balance the need for protection against radiation exposure with the practical limitations of water treatment and purification technologies.

**Why Each Wrong Option is Incorrect**
**Option A:** Gross alpha activity of 1.0 Bq/L and gross beta activity of 10.0 Bq/L are excessively high and would pose a significant risk to public health. These levels would likely exceed the recommended guidelines and potentially lead to radiation-induced health effects.

**Option B:** Gross alpha activity of 1.0 Bq/L and gross beta activity of 0.1 Bq/L are not consistent with the proposed guideline values. The gross alpha activity is higher than recommended, while the gross beta activity is lower than suggested.

**Option D:** Gross alpha activity of 10 Bq/L and gross beta activity of 1.0 Bq/L are significantly higher than the proposed guideline values. These levels would pose a substantial risk to public health and are not considered safe for consumption.

**Clinical Pearl / High-Yield Fact**
It is essential to note that these guideline values are subject to revision and may vary depending on the specific context and location. Healthcare professionals and water treatment specialists must stay up-to-date with the latest recommendations and guidelines to ensure the safe provision of drinking water.

**✓ Correct Answer: C. Gross a activity 0.1 Bq/L and Gross b activity 1.0 Bq/L**