Question

Complete the sentence with the most suitable option:
Within another hundred years, we will have to find alternative sources of energy, _________ the world's reserves of oil will not last that long.

• A. So that
• B. Since
• C. Unless
• D. While

Answer 1

Answer: (B)

Since

The conjunction is a word used to connect other words, phrases or clauses.

Subordinating conjunction connects or joins an independent clause with a subordinate clause.

'So that' is used to talk about a purpose.

'Since' shows one of the two associations: time or cause/reason. Here, since should be used to show the reason for reserves of oil not lasting that long. 'Unless' is used to mean 'except if'.

'While' means something that is happening at the same time as something else or indicates a contrast.

Thus, option B is the correct answer.