Option D: 10
$40 = 2^3 \times 5,\ 110 = 2 \times 5 \times 11,\ 360 = 2^3 \times 3^2 \times 5$. HCF = product of smallest powers of common prime factors = $2^1 \times 5^1 = \mathbf{10}$.
Source: Chapter 1, Section 1.2 (Fundamental Theorem of Arithmetic)
HCF is found by taking the lowest power of each prime factor common to all three numbers. Here, 2 and 5 are common to all three; their minimum powers are $2^1$ and $5^1$, giving HCF = 10. Note that 40 divides only 40 and 360 (not 110), so option A is wrong. Always check all three numbers share the factor.