Final answer:
Only statement b) 'They can be used for text messaging' is true about modern cellular phones; they use digital technology, come in various colors, and are widely used.
Step-by-step explanation:
The question asks to identify which statements about cellular phones are true. When discussing cellular technology, it's important to note that modern cell phones primarily use digital technology rather than analog, meaning statement a) is false. They certainly can be used for text messaging, as indicated in statement b), which has become a dominant form of communication, even surpassing voice calls, as mentioned in the provided references. Statement c) is incorrect because cellular phones are available in a wide range of colors, not just black. Lastly, statement d) is false because cellular phones are widely used and far from obsolete thanks to various technological advancements such as microwave transmission and communications satellites. Summing up:
- Cell phones use digital technology, not analog.
- Text messaging is a significant feature of cell phones.
- Cell phones are available in various colors.
- Cell phones are not obsolete and are in common use.