Answer: (b) Only two statements
Explanation: The article states that the Starberry-Sense star sensor can be used for small CubeSat class satellite missions, not just for astronomy missions. It also mentions that the Starberry-Sense star sensor uses a Raspberry Pi as its brain and costs less than 10% of other similar sensors available in the market. However, it does not state that the sensor cannot be used in CubeSat class satellite missions. Therefore, statements 1 and 4 are incorrect. Only statements 2 and 3 are correct.