ANS:B - less at equator than nearer the poles

The daily variation of magnetic declination is as much as 10^2. This variation is also known as Dirunal Variation. The following factors influence its magnitude:
(a) It is more in the day and less in the night.
(b) It is more in summer and less in winter.
(c) A number of variation changes from year to year.
(d) It is more near magnetic poles and less near the equator.