Correct option is a) 1.9%
Given
\(R = \frac{a^2\sqrt b}{c^4d}\)
Then
\(\left(\frac{\Delta R}R\right) = 2\left(\frac{\Delta a}a\right) + \frac12\left(\frac{\Delta b}b\right) + 4 \left(\frac{\Delta c}c\right) + \left(\frac{\Delta d}a\right)\)
\(\left(\frac{\Delta R}R\right)\times 100 = 2\left(\frac{\Delta a}a\right) \times 100 + \frac12\left(\frac{\Delta b}b\right) \times100+ 4 \left(\frac{\Delta c}c\right) + \left(\frac{\Delta d}a\right)\)
\(\left(\frac{\Delta R}R\right)\times 100 =\) 2 x 0.1% + \(\frac12\) x 0.2% + 4 x 0.3% + 0.4%
\(\left(\frac{\Delta R}R\right)\times 100 =\) 0.2% + 0.1% + 1.2% + 0.4%
\(\left(\frac{\Delta R}R\right)\times 100 =\) 1.9%