The correct answer is (b). Punjab is relatively poor in mineral resources compared to many other Indian states because it is dominantly alluvial plains. Alluvial plains are formed by the deposition of sediments from rivers. These sediments are typically not rich in minerals.
Option (a) is incorrect because there have been extensive geological surveys in Punjab. These surveys have identified a number of mineral deposits, but they have not been found to be economically viable.
Option (c) is incorrect because Punjab does not have a dense forest cover. In fact, the state has a relatively low forest cover of about 6%.
Option (d) is incorrect because there are no government restrictions on mining in Punjab. The state government has, in fact, been encouraging mining in recent years.
In conclusion, Punjab is relatively poor in mineral resources because it is dominantly alluvial plains. The sediments that form these plains are typically not rich in minerals.