To calculate the eutectic concentration, we need to understand the concept of eutectic points and how they relate to pressure and temperature. The eutectic point is the composition at which a eutectic mixture forms, which is a mixture of two or more substances that has a lower melting point than any other composition of those substances.

The eutectic concentration can be determined by considering the phase diagram of the given system. The phase diagram provides information about the different phases that exist as a function of temperature and composition.

In this case, we are given the pressure of 1 atm and the temperature of 1oC. We need to determine the eutectic concentration at this specific pressure and temperature.

Here are the steps to calculate the eutectic concentration:

1. Examine the phase diagram: Look at the phase diagram for the given system and identify the eutectic point. The eutectic point is typically denoted by a specific composition and temperature.

2. Determine the composition at the eutectic point: Once the eutectic point is identified, determine the composition at that point. This composition represents the eutectic concentration.

In this case, we are not given the specific phase diagram or any other information about the system. Therefore, we cannot determine the eutectic concentration based solely on the given data.

The correct answer cannot be determined without additional information.