Both sentences A and B are capitalized correctly:
Only one solution is possible: We must cut our expenses.
Only one solution is possible: we must cut our expenses.
The first word of both sentences (only) must always be capitalized since it is placed at the beginning.
On the other hand, if the sentence following the colon is dependent (it is incomplete), its first word should not be capitalized. For example:
"I have to buy three things: apples, oranges and bananas."
Regarding capitalization in independent clauses following a colon (such as the one given in the example), it is subject to the citation style the writer is following (APA, MLA, etc). While some styles recommend capitalization of the first word of the sentence, some others do not.
Answer:
When something takes place at the expected or established time, i.e. it is done according to the schedule, we use the word ‘on time’.
in time is used to denote soon enough, i.e. just before the end moment or before the expiry of the set time.
Explanation:
Examples:
We left for the airport on time.
I will reach the restaurant at 12 pm; please be on time.
Joseph set the alarm, to wake up in time, to study for exams.
We are sure that Joseph will finish the work in time.
