In making 1000 revolutions, a wheel covers 88 km.

(c) 28 m

Distance covered by the wheel in 1 revolution $=\left(\frac{88 \times 1000}{1000}\right) \mathrm{m}$

$=88 \mathrm{~m}$

We have:
Circumference of the wheel = 88 m
Now, let the diameter of the wheel be d m.
Thus, we have:

$\pi d=88$

$\Rightarrow \frac{22}{7} \times d=88$

$\Rightarrow d=\left(88 \times \frac{7}{22}\right)$

$\Rightarrow d=28 \mathrm{~m}$