Answer:
The correct answer will be option-A
Explanation:
A scientific question which is still not able to be known or remain unknown is known as an unknowable question.
Although many scientific technologies have been developed still some scientific questions remain unknown to us like the questions related to the religious beliefs and many practices based on the belief system.
The questions still remain unknown because "we are unable to collect the evidence or not able to observe the phenomenon". Since these cannot be observed, therefore, the question remains unknown.
Thus, option-A is the correct answer.
