Step 1: Understanding tachycardia.
Tachycardia refers to a heart rate that is faster than normal. In adults, a heart rate over 100 beats per minute is typically considered tachycardia.
Step 2: Analyzing the options.
(A) 60: This is the normal resting heart rate, not considered tachycardia.
(B) 95: This is within the normal range for heart rate and does not define tachycardia.
(C) 100: Correct — A heart rate of over 100 beats per minute qualifies as tachycardia.
(D) 75: This is within the normal heart rate range.
Step 3: Conclusion.
The correct answer is (C) 100, as tachycardia is defined as a heart rate over 100 beats per minute.