Step 1: Understand pencil grading system
Pencils are graded based on hardness (H) and blackness (B):
- The more Hs (e.g., 2H, 4H), the harder the pencil and lighter the line.
- The more Bs (e.g., B, 2B, 4B), the softer the pencil and darker the line.
Step 2: Compare all options
- 2H: Hard pencil, makes lighter lines.
- 4H: Even harder than 2H, even lighter lines.
- H: Medium-hard pencil, still not very dark.
- 2B: Softer than H, makes a darker line.
\[ $\Rightarrow$ \text{Among all options, 2B is the darkest pencil.}
\]
\[
\boxed{\text{Correct Answer: (B) 2B}}
\]
$PQ$ is a chord of length $4\ \text{cm}$ of a circle of radius $2.5\ \text{cm}$. The tangents at $P$ and $Q$ intersect at a point $T$. Find the length of $TP$.