Step 1 (Formula / Governing Law & Given Data): [1/4 Mark]
For a function $f(x)$ to be continuous at $x = a$, the limit of the function as $x$ approaches $a$ must be equal to the value of the function at $a$. Mathematically:
$$\lim_{x \to a} f(x) = f(a)$$Given $a = 0$, we must satisfy: $\lim_{x \to 0} f(x) = f(0) = k$.
Step 2 (Step-by-Step Mathematical Working): [1/2 Mark]
Substitute the given function into the limit definition:
$$\lim_{x \to 0} \left( \frac{\sin x}{x} + \cos x \right) = k$$Apply the limit properties (sum rule):
$$\lim_{x \to 0} \left( \frac{\sin x}{x} \right) + \lim_{x \to 0} (\cos x) = k$$Using standard limits ($\lim_{x \to 0} \frac{\sin x}{x} = 1$) and direct substitution for $\cos x$:
$$1 + \cos(0) = k$$ $$1 + 1 = k$$Step 3 (Final Concluded Answer): [1/4 Mark]
Therefore, the value of $k$ is:
$$k = 2$$The correct option is (D) 2.
💡 EL10 Concept Insight (Easy to Understand):
Think of continuity like drawing a line without lifting your pencil; for the line to be unbroken at zero, the "path" coming from both sides must land exactly on the point $k$. Since the path approaches 2, $k$ must be 2 to "fill the hole" and keep the line connected.