D – dawn. The dawn of something has idiomatic meaning of beginning or first stage of it.
B – about. ‘About’ is the most common preposition for ‘curiosity’. ‘Curiosity of’ would have a meaning that doesn’t fit this context – something that is interesting about a particular subject (e. g. ‘the curiosity of wildlife’)
B – pancake. An informal expression that means ‘very flat’. The shape of this food helps us pick the right answer even if we are unfamiliar with the original expression.
C – as. The only preposition that works well with the verb ‘to depict’. ‘To depict by’ would work as well, but it would point at the agent, the person or thing doing the action (e.g. ‘We can see this landscape here depicted by Da Vinci’)
C – being. The word ‘being’ is used here as gerund in the meaning of ‘existing’. However, option B can’t be used as it doesn’t fit grammatically in this context.
A – observation. The verb ‘make’ works well only with observation in the meaning ‘to see or notice something’. Option B shouldn’t be used as ‘to make notice’ is not a strong collocation, however you can say ‘to take notice’ which means taking something into consideration or if something comes to your attention.
B – Although. All four option introduce some contrast or counter-argument to the meaning. Options C and D do not fit grammatically, we would need something like ‘In spite of/Despite science having advanced…’. Option A can’t be used as it is an introductory word and therefore needs a comma.
C – accessible. The idea expressed here is that internet became easily available for most people.