Question

similarly, cross-country skiing offers excellent cardiovascular benefits when performed at a leisurely pace. people who begin to cross-country ski on a regular basis show a reduced heart rate over their first several weeks, indicating a strengthened heart with a more powerful ability to pump blood. yet there are solid indications that endurance cross-country skiing alters the structure of the heart, making it more susceptible to an arrhythmia. an arrhythmia is a condition in which the heart beats irregularly. people who suffer from arrhythmias are at a higher risk of blood clots in the heart and sudden cardiac arrest. one study from sweden examined 52,755 participants in an annual ninety-kilometer cross-country race over a nine-year period. it found that the participants with the most races completed and the fastest finishing times—the elite endurance skiers—suffered a higher
select the evidence that the author provides for the following supporting claim: extreme cross-country skiers are at a greater risk of developing heart problems.
in one study, elite endurance skiers were more likely to suffer from heart arrhythmias.
in one study, participants in cross-country skiing showed higher rates of heart arrhythmias than nonparticipants.
people who regularly cross-country ski show a reduced heart rate after a few weeks of training.
the high-calorie diets of cross-country skiers make them more susceptible to heart disease.

Explanation:

The text mentions a study on cross - country skiers. It specifically states that the elite endurance skiers (who are extreme in terms of their participation in cross - country skiing with most races completed and fastest finishing times) suffered a higher risk. The first option directly refers to elite endurance skiers (a subset of extreme cross - country skiers) and their higher likelihood of heart arrhythmias. The second option compares participants and non - participants (not specifically targeting extreme skiers). The third option is about a positive effect (reduced heart rate) which is not related to the risk claim. The fourth option about high - calorie diets is not mentioned in the given text.

Answer:

In one study, elite endurance skiers were more likely to suffer from heart arrhythmias.