**Core Concept**
The energy content of beverages, including tea, is determined by the amount of sugar added and the base calorie count of the beverage itself. Tea is generally low in calories, but adding sugar significantly increases the energy content.

**Why the Correct Answer is Right**
A cup of tea with the usual amount of sugar typically contains around 120 calories. This is because a single teaspoon of sugar contains approximately 16 calories, and most people add 2-3 teaspoons to their tea. The calorie count also accounts for the energy contribution from the milk, which is usually added to tea. The base calorie count of tea itself is negligible, around 0-2 calories per cup.

**Why Each Wrong Option is Incorrect**
**Option A:** 50 calories - This is an underestimation of the energy content of tea with sugar, as it does not account for the additional calories from milk.
**Option B:** 200 calories - This is an overestimation of the energy content of tea with sugar, as it does not accurately represent the typical amount of sugar added.
**Option C:** 80 calories - This is close to the actual calorie count, but still underestimates the energy contribution from sugar and milk.

**Clinical Pearl / High-Yield Fact**
When evaluating the energy content of beverages, remember that even seemingly low-calorie drinks can contribute significantly to daily energy intake, especially when sugar is added.

**Correct Answer:** B. 120 calories