Increase in the number of patients in the hospitals due to heat stroke is:

The question asks about the type of pattern that describes the increase in heat stroke patients in hospitals.

Secular Trend refers to long-term changes occurring over many years, such as population growth over decades or life expectancy increases over 50 years. Heat stroke cases do not increase permanently year after year; they fluctuate based on weather conditions.

Irregular Variation refers to random, unpredictable changes with no pattern, such as hospital admissions due to accidents or sudden disease outbreaks. Heat stroke cases are not random and can be predicted based on seasonal temperature changes.

Seasonal Variation refers to changes that repeat in a predictable pattern based on seasons or time of year. Heat stroke cases increase during summer months when temperatures are high and decrease during winter months when temperatures are low. This pattern repeats every year and is predictable.

Cyclic Variation refers to patterns that repeat over periods longer than a year, typically 5-10 years, such as economic cycles or business cycles. Heat stroke cases follow a yearly pattern, not a multi-year cycle.

Summer brings hot weather, leading to more heat stroke cases and increased hospital admissions. Winter brings cold weather, resulting in fewer heat stroke cases and decreased hospital admissions. This pattern repeats annually.

The answer is Seasonal Variation.

Heat stroke patient admissions follow a predictable, repeating pattern based on the seasons of the year, which defines seasonal variation.