A continuous frequency distribution of grouped data is represented graphically by a Histogram, where class intervals are taken on the horizontal X-axis and class frequencies on the vertical Y-axis, with adjacent rectangles whose areas are proportional to frequencies.

Why Option 2 is correct: A histogram is specifically designed to graphically depict continuous grouped frequency distributions without gaps between intervals.
Why Option 1 is incorrect: A pie chart is used to show proportions/percentages of categorical or discrete data, not continuous grouped frequency distributions.
Why Option 3 is incorrect: Pictograms use pictures or icons to represent discrete counts or qualitative data.
Why Option 4 is incorrect: Cartograms represent statistical data on geographical maps.

Given:
$P(\overline{B}) = 1/2 \implies P(B) = 1 - 1/2 = 1/2$
From the addition rule of probability: $P(A \cup B) = P(A) + P(B) - P(A \cap B)$

$$\frac{5}{6} = P(A) + \frac{1}{2} - \frac{1}{3} = P(A) + \frac{1}{6}$$ $$P(A) = \frac{5}{6} - \frac{1}{6} = \frac{4}{6} = \frac{2}{3}$$

Now evaluate the product $P(A) \times P(B)$:

$$P(A) \cdot P(B) = \frac{2}{3} \times \frac{1}{2} = \frac{1}{3}$$

Since $P(A \cap B) = 1/3 = P(A) \cdot P(B)$, the events $A$ and $B$ satisfy the condition for statistical independence.